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AGRICULTURAL 

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State  of  Connecticut 


REPORT 


OF 


The  Connecticut  Agricultural 
Experiment  Station 

FOR   THE  YEAR  1903 

PART  IV. 
REPORT  OF  THE  STATION  BOTANIST 


CONNECTICUT 

AGRICULTURAL  EXPERIMENT 
STATION 


REPORT  OF  THE  BOTANIST 

G.  P.  CLINTON,  S.D, 


J903 


C7^  1^03-1916 


EXPLANATION  OF  COLORTYPE 

Figures  about  natural  size 


1.  Leaf  Blight  on  Quincq  ;  see  page      ......  352 

2.  "  Cedar  Apple "  on  Cedar  branch  ;  seepage     .         .'        .  .  301 

3.  Red  Knot  on  bark  of  Kcelreuteria ;  see  page      ....  328 

4.  Loose  Smut  in  spike  of  Barley  ;  see  page  ....  306 

5.  Anthracnose  on  leaf  of  Chestnut;  seepage       .  .         .         .  315 

6.  Black  Dot  on  leaflets  of  Crimson  Clover  ;  see  page  .         .  316 

7.  Curl  on  Peach  leaf ;  see  page     .......  340 

8.  Leaf  Spot  on  leaflet  of  Strawberry  ;  see  page             .         .         .  360 
g.  Orange  Rust  on  leaflets  of  Blackberry  ;  see  page      .         .         .  309 

10.  Powdery  Mildew  on  leaf  of  Indian  Currant ;   see  page     .         .  327 

11.  Leaf  Spot  as  seen  on  upper  surface  of  Cherry  leaf  ;  see  page  .  314 

12.  Downy  Mildew  on  Lima  Bean  Pod  ;  see  page  .         .         .         .  307 

13.  Leaf  Blight  on  Corn  ;  see  page  ......  317 


DISEASES  OF  PLANTS  CULTIVATED  IN   CONNECTICUT.         2/9 

REPORT  OF  THE  BOTANIST.     , 


DISEASES   OF   PLANTS   CULTIVATED   IN   CON- 
NECTICUT. 

By  G.  p.  Clinton. 

Introduction.  Since  1889  the  botanists*  connected  with  the 
Experiment  Station  have  made  studies  of  many  of  the  troubles 
that  assail  our  cultivated  plants.  The  results  of  these  inves- 
tigations have  been  published  in  the  annual  reports  or  in  bul- 
letins, as  short  notes  or  as  more  extended  treatises.  During  the 
past  two  seasons,  the  writer  has  made  a  special  effort  to  gather 
together  from  different  parts  of  the  state  information  on  all  of 
the  diseases  of  our  cultivated  plants,  to  use,  with  the  previous 
data,  as  the  basis  of  the  present  report.  The  cultivated  plants  of 
Connecticut  fall  under  four  general  heads:  viz.,  i.  The  general 
farm  crops,  2.  The  horticultural  or  fruit  crops,  3.  The  market 
garden  crops,  4.  The  ornamental  plants.  Often  the  grower  is 
interested  only  in  one  of  these  lines,  but  usually  he  specializes 
less  and  includes  at  least  two.  An  attempt  has  been  made  to 
cover  all  of  these  industries  in  the  notes  reported. 

Causes. 

While  the  troubles  to  be  discussed  here  are  chiefly  those  pro- 
duced by  fungi,  it  will  be  well  to  note  briefly  the  chief  causes 
of  injuries  to  plants.  We  can  group  these,  somewhat  arbi- 
trarily, under  the  following  four  heads : 

I.  Mechanical  Injuries.  Under  this  head  may  be  placed 
such  injuries  as  result  from  some  sudden  mutilation  of  the  plant. 
Damage  by  wind  storms  is  of  this  character,  and  we  had  a  good 
illustration  of  the  injurious  nature  of  such  an  agent  to  our  fruit 
and  shade  trees  in  the  gale  of  last  September.  Lightning  is 
sometimes  the  cause  of  injury  to  shade  or  forest  trees,  opening 
the  way,  also,  for  future  decay  by  timber-rotting  fungi.  Forest 
fires,  while  not  occurring  often  on  a  large  scale  in  this  state, 
still,  sometimes  do  considerable  damage  to  local  wood  lots. 
Animals  are  agents  of  more  or  less  damage  to  plants.     Birds 

*  Prof.  R.  Thaxter,  1889-gi ;   Dr.  W.  C.  Sturgis,  1891-1901. 
19 


280        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

destroy  considerable  grain  and  fruit.  Mice  and  rabbits  often 
injure  fruit  trees  by  girdling.  Sometimes  cattle  go  where 
not  wanted,  with  destructive  results.  In  towns  the  injury  to 
our  street  trees  by  horses  is  very  evident.  See  Report  1900,  p. 
332.  Man,  himself,  is  often  a  mutilator  under  some  conditions 
when  installing  city  improvements. 

2.  Insect  Injuries.  These  might  be  classed  under  animal 
injuries,  but  the  damage  insects  cause  in  the  way  of  chewing, 
sucking  and  stinging  cultivated  plants  is  so  great  that  they 
deserve  notice  by  themselves.  It  is  not  the  purpose  to  treat 
of  these  here  since  the  entomological  reports  issued  from  time 
to  time  by  the  Station  deal  with  this  subject.  Since  the  fungi 
are  occasionally  classified  by  some  persons  as  "bugs,"  I  wish 
to  call  attention  to  the  fact  that  insects  as  agents  of  injury  to 
plants  are  entirely  different  from  f^l,ngi  as  disease-producers. 
Usually  the  troubles  caused  by  these  two  agents  can  be  distin*- 
guished  readily.  Holes  in'  the  leaves  or  wood  may  generally 
be  attributed  to  insects,  dead  spots  to.  the  fungi.  While  insects 
by  their  stinga  often  cause  a  morbid  growth,  they  are  not  true 
agents  of  decay  as  are  the  fungi  and  bacteria.  The  presence 
of  an  insect  at  the  place  of  injury  or  of  the  spore  stage  of  a 
fungus  usually  indicates  the  responsible  agent. 

3.  Physiological  Troubles.  These  are  often  obscure  as  to 
cause,  being  due  to  some  disturbance  of  the  natural  surround- 
ings of  the  plants,  and  are  generally  progressive  in  nature. 
Different  conditions  produce  different  troubles  and  as  yet  com- 
paratively few  have  been  studied  or  even  noted.  Cold  weather 
is  not  an  uncommon  cause  of  trouble  in  plants.  Injuries  from 
this  source  usually  result  from  a  mild,  late  fall  (in  which  the 
wood  of  plants  fails  to  ripen  thoroughly)  followed  by  a  sud- 
den severe  freeze,  as  that  of  December  9,  1902 ;  or  from  an 
unusually  severe  winter,  as  has  been  the  present ;  or  from  mild, 
open  winter  weather,  inducing  a  flow  of  sap,  followed  by  freez- 
ing weather;  or  from  an  early  spring,  inducing  premature 
blossoming,  followed  by  killing  frosts,  as  illustrated  somewhat 
by  the  spring  of  1902.  The  resulting  injuries  may  be  classed 
partially  as  mechanical,  as  the  sudden  death  of  the  fruit  buds, 
but  chiefly  as  physiological.  As  yet  we  do  not  sufficiently  know 
what  troubles  result  from  severe  but  not  fatal  injuries  to  the 
roots,  wood  and  cambium.     The  primary   effects   of  the   cold 


CAUSES  OF  PLANT  INJURIES.  28  I 

are  often  manifest  at  once  as  a  distinct  injury,  the  secondary- 
effects  may  be  obscured  in  later  developments,  possibly  cover- 
ing a  number  of  years.  The  effects  of  the  sudden  freeze  of 
December  9,  1902,  became  evident  at  once  or  during  the  past 
year  by  the  partial  destruction  of  privet  hedges ;  by  the  almost 
total  destruction  of  peach  fruit  buds,  also  by  the  death  of  some 
twigs  and  slight  injury  to  the  wood ;  by  the  girdled  areas  in  the 
bark  at  the  base  of  apple  trees ;  and,  in  some  nurseries,  by 
the  severe  injury  or  death  of  the  wood  of  young  fruit  trees, 
especially  apples,  without  apparent  injury  to  the  bark  or  cam- 
bium. During  the  past  severe  winter,  the  injury,  so  far  as 
observed,  has  been  the  partial  destruction  of  the  peach  fruit 
buds  and  the  very  great  injury,  or  even  death  in  some  orchards, 
of  the  wood,  showing  by  its  darkening  -color  down  to  the 
snow  line.  Heat  by  affecting  transpiration  of  moisture  may 
produce  wilting  of  foliage  or  tip  burn ;  in  greenhouses  it 
may  even  burn  spots  in  the  leaves,  probably  in  connection 
with  imperfect  glass  or  drops  of  water.  Water  when  present 
in  excess  in  the  soil  shuts  out  the  proper  circulation  of  air  and 
thus  causes  a  sickly  yellowish  plant  growth  or  drowns  it  out 
entirely.  In  the  shape  of  rain  and  dew  it  is  the  chief  factor 
in  the  spreading  of  fungous  diseases.  Fertilizers,  when  used 
carelessly,  sometimes  burn  the  foliage,  injure  the  roots  or  often 
kill  the  germinating  seedlings.  On  the  other  hand,  the  lack 
of  the  proper  elements  of  fertility  in  the  soil  manifests  itself  in  a 
scanty  or  sickly  plant  growth.  Ensyms,  or  chemical  ferments, 
produced  in  plants  through  a  disturbance  of  their  normal  activi- 
ties and  causing  a  diseased  condition  of  the  tissues  containing 
them,  are  now  given  as  the  cause  of  such  obscure  troubles  as 
peach  yellows,  calico  tobacco,  yellows  of  asters,  etc.  Such 
troubles  are  sometimes  transmitted  and  are  said  to  be  produced 
by  "running  out  of  the  stock,"  by  unfavorable  mechanical  con- 
ditions in  the  soil,  etc. 

4.  Fungous  Diseases.  It  is  the  comparatively  few  physio- 
logical troubles  and  the  very  numerous  fungous  diseases  that 
this  article  treats.  The  latter  have,  as  the  agents,  what  are 
commonly  called  parasitic  fungi.  A  fungus  is  a  plant  as  truly 
as  are  the  flowering  plants,  but  it  is  low  down  in  the  vegetable 
kingdom,  lower  even  than  is  the  insect  in  the  animal  world. 
Let  us  consider  more  fully  the  nature  of  these  fungi,  their 


282        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

effect  upon  vegetation  as  producers  of  disease,  and  the  methods 
employed  in  combating  them.  [See  Reports  1889,  pp.  1.27-9; 
1897,  p.  182;    1900,  p.  255.] 

Parasitic  Fungi. 

Nature  of  Fungi.  As  has  just  been  stated,  fungi  are  low 
in  the  plant  kingdom,  in  fact,  among  the  lowest  and  conse- 
quently of  rather  simple  structure.  Many  of  them  are  micro- 
scopic in  size,  while  the  largest  are  represented  by  the  shelf 
fungi,  toadstools  and  puffballs.  They  differ  from  the  higher 
groups  (the  algae,  mosses,  ferns  and  flowering  plants)  in  that 
they  lack  chlorophyll  or  the  green  coloring  matter  that  enables 
these  other  plants  to  manufacture  their  food  directly  out  of 
the  air,  water  and  soil.  They  must  in  consequence,  like  ani- 
mals, obtain  their  food  already  in  an  organized  state  from 
organic  matter.  When  they  obtain  this  from  dead  vegetable 
or  animal  matter,  they  are  known  as  saprophytes,  examples  of 
which  are  the  common  household  molds,  puffballs  and  toad- 
stools. When  they  get  it  from  the  living  plant,  or  animal 
occasionally,  they  produce  disease  and  are  called  parasitic  ftmgi, 
as  the  various  blights,  rusts,  smuts,  mildews,  leaf  spots,  etc. 
The  line  separating  parasitic  and  saprophytic  fungi  is  not  very 
sharply  marked,  for  many  parasites  have  stages  that  are  sapro- 
phytic, and  some  species,  ordinarily  saprophytes,  may  under  cer- 
tain conditions  act  as  parasites.  In  general  two  structural  parts 
are  recognized  in  fungi ;   namely,  the  mycelium  and  the  spores. 

Mycelium.  This  is  the  vegetative  part  of  the  fungus  (cor- 
responding in  function,  in  a  general  way,  to  the  roots,  stems 
and  leaves  of  the  higher  plants)  since  it  is  largely  concerned 
in  gathering  food.  As  stated  before,  it  does  not  manufacture 
this  food  but  gets  it  directly  from  the  host  (the  plant  or  animal 
upon  which  it  grows),  either  from  food  intended  for  the  latter's 
use,  or  as  the  result  of  the  disorganization  of  the  plant's  cells 
or  cell  contents  by  enzyms,  or  through  the  formation  of  morbid 
plant  growths.  The  disease  thus  induced  may  be  very  local 
or  widespread  and  it  may  become  evident  at  once  or  only  after 
considerable  time.' 

In  general  the  m3^celium  consists  of  microscopic  threads, 
becoming  more  or  less  branched.  The  gross  aspect  is  shown 
by  the  spawn  that  ramifies  through  the  soil  from  the  base  of 


NATURE   AND    STRUCTURE   OF   FUNGI.  283 

the  toadstool.  These  threads  are  divided  more  or  less  by  cross 
partitions  into  cells  which  are  usually  elongated.  Generally 
the  threads  of  the  mycelium  ramify  loosely  through  the  sub- 
stratum but  sometimes  they  are  compacted  into  masses.  The 
cells  when  young  are  filled  with  protoplasmic  and  other  con- 
tents but  with  age  the  contents  become  limited  to  the  walls  or 
to  scattered  granules.  The  mycelium  is  generally  colorless. 
Sojnetimes  it  is  confined  almost  entirely  to  the  exterior  of  the 
host,  only  sending  short  food-gathering  branches,  haustoria, 
within,  as  with  the  powdery  mildews ;  but  usually  this  condi- 
tion is  reversed  and  the  mycelium  is  entirely  concealed  within 
the  host,  running  between  or  often  directly  into  the  plant  cells, 
and  becoming  evident  on  the  exterior  only  when  specially  modi- 
fied parts  give  rise  to  the  spore  stage.  As  a  rule,  then,  the 
mycelium  is  not  very  evident  or  characteristic  in  the  different 
fungi. 

Spores.  These  are  the  reproductive  bodies  and,  roughly 
speaking,  correspond  in  function  to  the  seeds  of  the  flowering 
plants.  They  are  formed  on  or  from  modified  threads  of  the 
mycelium,  usually  at  or  on  the  surface  of  the  host.  While 
microscopic  in  size,  the  spores  are  usually  produced  in  such 
abundance  as  to  be  evident  to  the  naked  eye.  Thus  in  the 
rusts  and  smuts  the  reddish  or  blackish  outbreaks  are  made  up 
entirely  of  these  bodies.  Often  they  consist  of  a  single  cell, 
varying  in  shape,  size  and  character  of  the  wall  in  different 
species ;  not  infrequently  they  are  composed  of  two  to  many 
cells  variously  combined,  of  which,  occasionally,  only  part  are 
fertile.  So  great  are  these  variations  that  those  of  each  species 
usually  have  some  individuality  by  which  they  can  be  recog- 
nized and  it  is  chiefly  upon  these  spore  differences  that  the 
fungi  are  classified. 

Very  curiously  each  fungus  generally  has  more  than  one, 
kind  of  spores,  sometimes  as  many  as  four  or  five  kinds.  These 
spores  are  of  two  types,  summer  and  winter  spores.  The 
■summer  spores  are  usually  thin-walled,  germinate  readily  and 
are  produced  on  the  external  parts  of  the  host  in  great  abun- 
dance, to  be  easily  scattered.  Their  object  is  to  spread  the 
disease  to  the  same  or  other  plants  during  the  growing  season. 
The  winter  spores,  on  the  other  hand,  are  not  produced  so 
abundantly,  are  often  buried  more  securely  within  the  tissues, 


284        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O3. 

and  if  not  thick-walled  are  formed  within  sacs  and  receptacles 
that  protect  them  to  a  great  degree  from  moisture  and  cold. 
Frequently  they  will  not  germinate  until  the  following  spring. 
Their  evident  function  is  to  carry  the  fungus  over  the  unfavor- 
able period  of  winter  weather.  Mycelium  in  the  perennial  parts 
of  the  plant,  also,  may  serve  this  same  purpose,  as  in  the  case  of 
the  orange  rust  of  blackberry. 

The  different  kinds  of  spores  are  produced  at  different 
times  of  the  year,  usually  the  summer  spores  in  spring  and 
summer  and  the  winter  spores  in  summer  and  fall.  Thus,  the 
red  (summer)  stage  of  rusts  precedes  the  black  (winter)  stage. 
This  peculiarity  is  carried  a  step  further  when  we  find  one 
spore  stage  developing  parasitically  and  another  saprophytically. 
Thus,  in  apple  scab  the  summer  spore  stage  exists  as  the  "scab" 
of  the  living  leaves  and  fruit  while  the  winter  stage  develops 
on  the  dead  leaves  in  the  fall  and  following  spring.  The  separa- 
tion of  the  spore  stages,  however,  becomes  widest  when  they 
occur  on  entirely  different  host  plants,  one  producing  the  other. 
Such  is  the  case  of  the  cedar-apple  rusts  and  the  barberry- 
wheat  rust. 

To  solve  the  complete  life  history  of  a  fungus,  therefore, 
often  becomes  a  considerable  problem.  It  is  because  of  these 
complications  that  botanists  have  often  described  different  stages 
of  the  same  fungus  as  distinct  species.  There  are  many  para- 
sitic fungi  of  which  only  the  summer  spore  stages  are  known 
but  which  are  suspected  of  having  saprophytic  winter  spore 
stages,  since  detailed  study  of  related  forms  has  often  brought 
these  to  light. 

Fungi  infect  their  host  through  the  germination  of  the  spores. 
Moisture  in  the  shape  of  rain  or  dew  is  necessary  to  induce  this. 
Usually  the  germination  must  take  place  on  certain  parts  of 
the  plant  in  order  to  secure  entrance.  Often  the  parts  per- 
mitting infection  are  quite  localized  but  more  often  it  is  a  ques- 
tion of  the  tissues  being  in  a  young  state  and  thus  easy  of 
penetration.  The  common  method  of  infection  is  for  the  spore 
to  send  out  a  short  germ  thread  which  enters  the  plant 
through  the  stomates  (breathing  spores)  or  else  bores  directly 
through  the  tissues.  Once  inside,  this  thread,  by  growth,  gives 
rise  to  the  extended  mycelium.  Comparatively  few  spores  meet 
conditions  that  insure  infection  of  the  host,  hence  the  neces- 
sity to  the  fungus  of  great  numbers  of  spores. 


NATURE   AND    STRUCTURE   OF   FUNGI.  285 

Relation  to  weather.  We  have  remarked  on  the  importance 
of  moisture  to  germination  of  spores  and  consequent  infection 
of  hosts.  The  character  of  the  weather  thus  bears  important 
relation  to  the  spread  of  plant  diseases,  especially  with  certain 
kinds  at  special  times.  It  is  not  the  amount  of  rain  that  falls 
that  is  most  important  but  the  time  it  takes.  For  example, 
a  few  days  of  moist  weather  with  comparatively  little  rain  but 
also  with  little  sunshine  to  dry  away  the  moisture  from  the 
foliage  is  evidently  more  favorable  for  spreading  these  troubles 
than  a  violent  rain  storm  followed  the  same  day  by  bright  sun- 
shine. Cloudy  weather,  by  hindering  evaporation  of  the  water 
'transpired  by  the  leaves,  may  aid  in  the  spread  of  disease. 

In  its  relation  to  different  diseases  of  plants,  the  season 
of  the  moist  weather  is  very  important.  For  instance,  a 
rainy  April-May  period  is  very  favorable  for  apple  rust;  a 
cold,  moist  May  or  June  aids  decidedly  the  introduction  and 
spread  of  apple  or  pear  scab.  The  fruit  grower  dreads  moist 
weather  during  the  ripening  and  harvesting  period  of  his  peach 
and  plum  crop,  since  brown  rot  flourishes  chiefly  at  this  time. 
The  market  gardener  is  specially  anxious  about  the  rainy  week 
that  may  come  in  July  or  August  and  blight  his  potato  vines, 
and  which,  if  followed  with  additional  rainy  weather,  is  likely 
to  rot  the  tubers ;  or  of  wet  August  and  September  weather 
that  produces  stem  rot  in  his  onions.  The  downy  mildews  are 
especially  lovers  of  moisture,  and  so  the  musk  melons  and 
cucumbers  have  suffered  from  one  of  these  troubles  during  the 
past  three  years,  because  of  their  moist  summers. 

Water  affects  the  spread  of  fungous  diseases  in  three  ways : 
First,  many  fungi,  especially  the  stages  producing  thin-walled, 
ephemeral  spores,  produce  these  only  or  most  vigorously  during 
moist  weather.  Second,  the  rain,  in  a  measure,  acts  as  a  distrib- 
uting agent,  washing  the  spores  over  different  parts  of  the 
plant.  Third,  water,  as  has  been  stated  before,  is  needed  for 
the  germination  of  the  spores. 

Injury  and  Loss.  It  is  evident  from  what  has  been  written 
that  parasitic  fungi  often  become  agents  of  serious  disease  in 
plants  and  thus  cause  greater  or  less  financial  loss  to  the  hus- 
bandman. It  is  not  the  intention  to  present  an  array  of  figures 
showing  the  losses  caused  by  these  parasites  in  Connecticut,  for 
startling  as  these  might  look,  they  are  not  nearly  so  suggestive 


286        CONNECTICUT    EXPERIMENT    STATION    REPORT^    I903. 

to  the  grower  as  some  personal  recollection  he  may  have  of 
local  losses.  Occasionally  one  hears  the  remark,  "Fungous 
troubles  are  much  worse  than  formerly.  We  never  used  to  be 
bothered  so  by  them."  Very  often  this  statement  is  incited  by  a 
season  that  has  been  especially  favorable  for  such  troubles,  or 
is  drawn  forth  by  an  unusual  personal  loss.  Where  plant  grow- 
ing is  intensified,  as  it  is  in  Connecticut,  we  may  reasonably 
expect  more  trouble  from  fungous  pests  than  occurred  in  the 
earlier  days  when  farms  were  more  scattered,  importations 
limited  and  crops  less  specialized.  We  should  bear  in  mind, 
however,  that  agitation  and  information  now  make  losses  seem 
more  prominent  than  formerly,  since  then  the  grower  knew  less  • 
of  the  why  and  wherefore  of  his  troubles,  attributing  them,  per- 
haps, wholly  to  season  and  luck. 

Some  of  the  pests  causing  serious  loss  during  recent  years  may 
be  briefly  mentioned.  Brown  rot  of  peaches  and  plums  is  always 
present  at  harvest  time,  some  seasons  becoming  so  prevalent  that 
it  sweeps  away  a  large  part  of  the  profits  in  a  few  days.  The 
past  year  produced  a  small  peach  crop  and  this  accounts  in  part 
for  the  small  amount  of  rot,  even  in  early  varieties,  as  the  fruit 
of  heavily  laden  trees  always  rots  more  or  less  because  of  the 
facility  for  spreading  the  disease.  Scab  or  black  spot  is  another 
trouble  of  the  peach  that  attracts  the  attention  of  the  grower,  for, 
while  it  is  not  primarily  an  agent  of  decay,  it  causes  the  fruit 
to  become  second  class  in  appearance,  often  smaller  in  size  or 
one-sided,  and  by  cracking  it,  opens  the  way  for  decay.  This 
trouble  seemed  to  be  worse  than  usual  the  past  season.  Black 
knot  of  plums  and  cherries  is  an  old  trouble  that  proved  more 
prominent  than  usual  last  year.  This  is  one  of  the  few  fungous 
diseases  against  which  laws  have  been  directed  in  some  states. 
Downey  mildew  or  blight  of  potatoes  during  the  past  two  years 
has  prematurely  killed  the  vines  in  July  or  August,  thus  cutting 
down  the  crops  of  the  late  varieties  25  to  50  per  cent.,  for  the 
vines  should  have  lived  until  killed  by  the  September  frosts. 
During  the  past  season  rot  of  the  tubers,  following  the  blight, 
added  to  the  loss  and  attracted  considerable  attention  among  the 
growers.  Stem  rot  of  the  White  Globe  onions  has  now  been 
very  bad  for  two  years  and  has  almost  discouraged  the  grow- 
ing of  this  popular  and  otherwise  very  profitable  variety.  In 
the  vicinity  of  Green's  Farms  and  Southport  in  1902,  the  loss 


CLASSIFICATION    OF    FUNGI.  28/ 

was  reported  to  be  in  the  vicinity  of  $50,000,  and  last  year 
some  growers,  after  marketing  part  of  the  crop  with  returns 
little  greater  than  the  freight  charges,  threw  away  the  remain- 
der. The  Downy  Mildew  and  other  troubles  of  the  musk  melon 
have  proved  so  serious  during  recent  years  that  many  have 
given  up  growing  this  plant.  The  greenhouse  man  has  his 
special  troubles  with  the  leaf  spot  of  violets,  rusts  of  carnation 
and  chrysanthemum,  mildew  and  leaf  spot  of  rose  and  the  vari- 
ous stem  rots,  and  sometimes  the  local  loss  caused  by  one  or 
more  of  these  fungi  becomes  considerable. 

Classification.  Botanists  have  classified  the  fungi  under 
various  groups  according  to  their  relationships.  Some  of  these 
groups  contain  only  forms  that  are  of  little  economic  impor- 
tance, but  the  chief  divisions  all  contain  at  least  some  important 
parasitic  forms.  The  scientific  name  of  a  plant  conveys  some 
idea  of  its  nature  and  relationships.  Dr.  Sturgis  in  his  Litera- 
ture of  Fungus  Diseases  [see  Reports  1893,  p.  253 ;  1900, 
255]  aimed  to  apply  the  common  names  somewhat  similarly,  so 
that  the  terms  rust,  smut,  blight  are  applied  only  to  certain 
related  forms  and  not  used  indiscriminately.  Since  in  the  fol- 
lowing notes  this  plan  has  been  largely  followed,  it  may  be 
profitable  to  discuss  briefly  a  popular  classification  of  these 
chief  groups : 

Slime  Molds.  Some  scientists  place  these  forms  with  the 
animals,  and  strictly  considered  they  are  related  to  rather  than  a 
group  of  true  fungi.  Ordinarily  they  occur  as  saprophytes  that 
are  found  chiefly  on  decaying  stumps  in  the  woods  during 
moist  weather.  At  first  they  consist  of  brightly  colored  naked 
masses  of  protoplasm  that  ooze  out  in  jelly-like  masses  on  the 
wood,  but  in  a  dry  atmosphere  these  soon  change  into  clustered 
spore-bearing  bodies.  They  are  mentioned  here  because  at  least 
two  forms  are  parasitic;  viz.,  club-root  of  cruciferous  plants 
and  crown-gall  of  fruit  trees.  In  both  of  these  diseases  there 
is  a  morbid  growth  of  the  infected  tissues  of  the  host  but  there 
is  no  evidence  to  the  naked  eye  of  the  causal  agent.  See  Plates 
XV,  a ;  XXIV,  b. 

Bacteria.  These,  also,  are  hardly  true  fungi  but  are  very 
closely  related  to  the  lowest  forms  and  for  all  practical  pur- 
poses may  be  considered  with  them  here.  Bacteria  as  agents 
of    contagious    diseases    in    animals,    especially    in    man,    are 


288        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

recognized  as  very  important  organisms.  While  the  diseases 
produced  in  plants  are  comparatively  few,  these  are  usually  of 
importance  and  are  very  properly  designated  blights.  They 
cause  the  death  of  the  tissues  invaded  and  these  often  assume 
a  semi-water-soaked  appearance.  No  sign  of  the  bacteria  is 
seen  save  occasionally  in  the  sticky  slime  that  oozes  out  on  the 
surface.  Examining  this  under  the  microscope,  we  see  myriads 
of  these  smallest  and  simplest  of  living  organisms — mere 
rounded  or  elongated  cells  too  small  to  be  seen  save  with  the 
highest  powers.  Insects  are  very  important  factors  in  the  dis- 
tribution of  these  germs  and  they  are  among  the  most  difficult 
troubles  to  control.  Prominent  examples  are  pear  blight,  bean 
leaf  blight  [Plate  XIII,  d],  blight  or  wilt  of  cucurbits  [Plate 
XXVI,  a]  and  wet  rot  of  potatoes  [Plate  XXII,  a].  Some 
bacteria  are  useful,  as  soil  bacteria,  those  producing  root  tubercles 
on  leguminous  plants,  those  giving  flavor  and  aroma  to 
butter,  etc. 

Thread  Fungi  (including  Downy  Mildews).  This  group 
includes  a  miscellaneous  lot  of  fungi  of  which  only  the  Downy 
Mildews  are  of  economic  importance  in  this  state.  These  mil- 
dews are  usually  distinguished  by  the  rather  dense  whitish 
growth  they  form  on  the  outside  of  the  infected  parts.  See 
Plate  XIII,  b.  Examining  this  under  the  microscope,  it  is  found 
to  consist  of  erect  fertile  threads  having  a  special,  often  tree-like, 
branching  above,  on  the  tips  of  which  the  thin-walled  summer 
spores  are  borne  singly.  Less  commonly,  these  fungi  form 
large,  thick-walled,  dark  colored  winter  spores  embedded  in  the 
tissues,  from  which  they  are  liberated  only  by  decay.  Promi- 
nent examples  of  the  downy  mildews  are  blight  of  potatoes 
[Plate  XXIII,  a],  downy  mildew,  or  blight  of  melons  and 
cucumbers  [Plate  XVIII,  b],  and  the  downy  mildews  of  lima 
beans  [Plate  XIII,  b],  and  of  grapes  [XVII,  b]. 

Smuts.  The  smuts  cause  very  important  diseases  of  the 
cereals,  especially  in  the  central  and  northwestern  part  of  this 
country.  As  their  name  indicates,  they  are  ordinarily  distin- 
guished by  the  "smutty"  outbreaks  on  various  parts  of  the 
host,  most  commonly  occurring  in  the  floral  parts.  Some 
species,  the  white  smuts,  of  which  few  are  of  economic  impor- 
tance, are  permanently  embedded  in  the  tissues  and  lack  this 
dusty  character.     These  outbreaks  are  made  up  entirely  of  the 


CLASSIFICATION    OF   FUNGI.  289 

spores.  The  spores  are  usually  single  cells,  but  may  consist 
of  several  cells  united  into  a  ball,  which  sometimes  is  covered 
with  a  coating  of  sterile  cells.  The  spores  in  germinating  often 
give  rise  to  secondary  spores,  after  the  fashion  and  nature  of 
the  yeast  fungus,  and  these  help  greatly  in  spreading  the  fungus. 
In  the  case  of  corn  smut,  for  instance,  these  secondary  spores 
are  capable  of  existing  and  multiplying  sapropyhytically  in 
manure.  In  this  state,  the  most  injurious  smuts  are  those  of 
onion,  corn  [Plate  XVI,  b],  oats  [XIX,  e]  and  barley  [XIII,  a]. 

Rusts.  Rust  is  a  term  often  used  by  growers  to  indicate  any 
spotting  of  foliage,  but  as  restricted  here,  it  is  applied  to  those 
small,  reddish  or  blackish  outbreaks  on  leaves  and  stems  that 
are  somewhat  similar  to  the  smuts  but  usually  less  dusty  and 
often  quite  firm.  They  form  a  very  common  and  large  group, 
and  include  some  of  the  most  injurious  of  our  parasites.  In 
this  state,  the  economic  species  include  such  examples  as  apple 
rust  [Plate  XI,  c],  oat  rusts  [Plate  XIX,  c-d],  carnation  [Plate 
XV,  b]  hollyhock  [XVII,  d],  bean  [Plate  XIII,  e]  rusts,  etc. 
The  rusts  are  especially  interesting  because  their  spore  forms 
may  occur  on  different  hosts.  Let  us  illustrate  this  with  the  case 
of  the  black  stem  rust  of  oats :  spermatia,  inconspicuous,  sup- 
posed spore  stage,  on  upper  surface  of  barberry  leaves ;  I, 
aecidio-spores  borne  on  the  under  surface,  beneath  the  above, 
in  the  cluster  cups ;  II,  or  uredo-spores,  forming  the  reddish 
outbreaks  on  the  stems  of  oats  in  early  summer ;  III,  or  teleuto- 
spores,  forming  the  black,  less  dusty,  outbreaks  on  these  same 
stems  later  in  the  season.  Some  rusts  possess  only  one  or  two 
of  these  stages.  In  the  case  of  the  apple-leaf  rust,  the  aecidial 
or  summer  spores  occur  on  the  apple  leaves  and  the  teleutal  or 
winter  spores  on  the  cedar  in  the  ''cedar  apples." 

Fleshy  Fungi.  These  are  the  most  conspicuous  fungi,  includ- 
ing the  toadstools,  shelf  fungi,  puffballs,  etc.  The  "spawn" 
of  the  cultivated  toadstool  is  the  mycelium,  and  it  is  perhaps 
chiefly  by  this  that  these  fungi  are  carried  over  the  winter.  The 
toadstool  itself  is  the  fruiting  body,  bearing  the  thin-walled 
spores  on  the  surface  of  the  gills,  that  radiate  out  on  the  under 
side  of  the  cap.  In  the  puffballs,  the  dusty  cloud  that  puffs 
out  on  pressure  is  composed  of  the  spores.  These  forms  are 
largely  saprophytic,  getting  their  food  from  the  humus  of  the  - 
soil  or  dead  wood.     Some  species  are  parasitic  on  trees ;  the 


290        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

injury  done  to  trees  and  timber  by  the  mycelium,  causing  dry 
rot,  is  very  considerable. 

Sac  Fungi  (including  Poivdery  Mildews).  Under  this 
group  come  a  great  variety  of  fungi,  including  some  of  our 
most  destructive  parasites.  They  are  distinguished  micro- 
scopically by  the  fact  that  their  winter  spores,  often  eight  in 
number,  are  borne  inside  of  sacs  or  asci,  and  these  in  turn  are 
enveloped,  partially  or  wholly,  by  a  special  receptacle.  The 
powdery  mildews  constitute  one  of  the  most  distinct  and  impor- 
tant groups  of  this  class.  They  are  characterized  by  their 
mycelium  developing  on  the  exterior  of  the  host,  showing  as  a 
cobweb-like  or  cottony  growth.  The  summer  spores  are  pro- 
duced on  this  in  upright  chains.  The  winter  spores,  asco-spores, 
are  formed  inside  the  small  yellowish  or  blackish  balls,  perithecia, 
that  can  be  seen  with  a  lens,  or  often  by  the  naked  eye, 
embedded  in  the  mycelium.  See  Plate  XV,  c.  The  great  varia- 
tion in  the  character  of  the  sac  fungi  is  shown  by  the  following 
examples:  powdery  mildews  of  cherry  [Plate  XV,  c],  phlox 
[Plate  XXIV,  a],  and  rose  [Plate  XXV,  a]  ;  black  knot  [Plate 
XXIV,  c],  black  rot  [Plate  XVII,  a],  ergot  [Plate  XXV,  b]. 
Not  uncommonly  the  summer  spore  stages  of  this  class  of 
fungi  are  serious  parasites,  while  the  winter  spore  stages  develop 
merely  as  saprophytes,  as  in  the  case  of  apple  scab,  bitter  rot 
and  brown  rot. 

Imperfect  Fungi.  These  are  so-called  because  only  summer 
spore  stages  are  known.  They  are  suspected,  for  the  most  part, 
to  be  merely  stages  of  the  sac  fungi,  and  every  once  in  a  while 
these  winter  stages  are  found,  as  recently  in  the  case  of  bitter 
rot  of  apples  and  brown  rot  of  peaches.  Under  this  group 
come  many  of  the  leaf  blights,  leaf  spots,  anthracnoses,  molds, 
etc.  Common  examples  are  sooty  blotch  of  apple  [Plate  XI,  b], 
black  rot  of  quince,  anthracnose  of  bean  [Plate  XIII,  c],  potato 
scab  [Plate  XXII,  c],  leaf  spot  of  violet  [Plate  XXVIII,  d],  etc. 

Prevention. 
It  has  become  evident  to  the  reader  who  has  followed  us 
thus  far,  that  the  fungous  troubles  of  Connecticut  are  of  suf- 
ficient importance  to  demand  the  efforts  of  the  grower  to  lessen 
their  ravages.  What  are  some  of  the  methods  that  may  be 
employed  to  control  them? 


PREVENTION    OF   DISEASES    CAUSED   BY    FUNGI.  29 1 

Selection.  The  first  requisite  for  good  plants  is  Good  seed, 
spelled  with  a  capital  G.  Aside  from  any  physiological  advan- 
tage that  large,  plump,  thoroughly  matured  seeds  may  have  over 
smaller  shrivelled  ones,  the  former  are  less  likely  to  come  from 
diseased  plants  or  to  carry  disease  germs  than  are  the  latter. 
In  some  cases  it  is  desirable  to  know  the  origin  of  the  seed,  for 
in  the  case  of  the  grain  smuts,  the  spores  adhere  mechanically 
to  the  seed.  Evidently,  seed  from  a  field  free  from  smut  is 
to  be  preferred  to  that  from  a  very  smutty  field,  though  the 
seed  may  look  as  good.  Potato  tubers,  though  not  strictly  seed, 
come  under  this  class.  Use  scabby  tubers  and  the  resulting 
crop  will  be  more  or  less  scabby,  according  to  the  season.  The 
same  principle  holds  true  of  nursery  stock.  Buy  of  the  most 
reliable  firms,  avoid  purchase  from  nurseries  where  certain 
troubles  are  known  to  be  bad ;  inspect  the  stock  when  it  comes 
and  discard  the  poor,  especially  if  it  shows  knots  or  diseased 
areas.  Selection  of  varieties  may  aid  in  some  cases  to  keep 
down  specific  troubles,  since  it  is  well  known  that  varieties  vary 
in  susceptibility  to  disease.  For  example,  in  a  recent  visit  to 
a  nursery,  the  writer  saw  Wealthy  and  Fallowater  apples  abun- 
dantly covered  with  leaf  rust,  while  all  of  the  other  varieties 
in  the  same  block  of  trees  were  free.  Greenhouse  growers  well 
know  that  there  is  wide  difference  among  the  carnations  in 
rusting.  Our  government  botanists  have  even  taken  up  the  task 
of  rearing  disease  proof  varieties  to  certain  diseases  hy  selection 
and  breeding.  Along  this  line,  the  writer  recalls  what  was  told 
him  by  an  eastern  asparagus  grower  who  was  troubled  with 
rust.  He  said  he  noticed  in  a  certain  spot  of  a  neighbor's 
field  that  a  few  asparagus  plants  always  remained  green  after 
the  others  were  dying  from  the  rust.  He  obtained  plants  from 
that  place,  and  was  gradually  building  up  a  bed  to  determine 
if  he  could  secure  exemption  from  the  disease  by  obtaining 
a  rust-proof  variety.  He  may  or  may  not  succeed,  but  his 
experiment  costs  him  little  to  determine  this  point.  Selection 
of  ground  certainly  counts  in  those  cases  where  disease  has 
become  established  in  the  soil.  A  rational  system  of  rotation 
must  be  adopted  to  prevent  or  lessen  such  troubles  as  onion 
smut,  potato  scab,  club  root,  etc.  Through  continued  use, 
especially  with  the  same  crop,  the  soil  of  the  greenhouse  may 
become  infected  with  stem  rot,  drop  and  other  fungous  troubles. 


292        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

Cleanliness.  It  is  easier  to  write  about  ideal  farm  methods 
than  it  is  tO'  carry  them  out ;  nevertheless,  no  one  will  deny- 
that  cleanly  methods  are  the  best.  Thorough  culture  not  only 
destroys  weeds,  conserves  moisture,  but  it  aids  in  the  quicker 
destruction  of  old  leaves,  etc.,  that  may  be  harboring  the  dis- 
ease germs  of  last  year's  crop.  Refuse  of  the  present  crop, 
especially  when  diseased,  if  left  on  the  land,  becomes  a  menace 
to  succeeding  crops  of  a  similar  nature.  When  one  sees  a  turnip 
field  in  which  the  owner  has  very  carefully  gathered  all  of  the 
roots  except  those  "clubbed,"  he  feels  confident  that  the 
grower  is  helping  along  the  trouble  in  the  future  use  of  that 
field  for  a  similar  crop.  So,  too,  a  field  left  covered  with  anthrac- 
nosed  melons  does  not  help  the  success  of  future  crops.  The 
manure  pile  is  a  very  essential  feature  to  successful  plant  grow- 
ing, but  it  should  not  he  made  a  refuse  pile  upon  which  diseased 
vegetable  matter  is  dumped.  It  will  never  do  any  harm  to 
gather  carefully  all  rotting  fruit  and  refuse  stems  from  the 
garden  or  orchard  at  the  close  of  the  season ;  it  will  do  good, 
but  the  place  to  put  them  is  in  the  bonfire. 

Pruning.  With  certain  diseases,  the  best  treatment  consists 
in  the  removal  of  the  affected  parts.  In  pruning  pear  trees  for 
blight,  or  plums  for  black  knot,  one  must  cut  off  the  infected 
branches  so  as  to  include  all  of  the  diseased  wood.  Aside  from 
the  removal  of  the  diseased  limbs,  pruning  is  useful  by  letting 
in  air  and  sunlight  to  aid  in  the  rapid  evaporation  of  moisture 
and  thus  hinder  infection  from  germinating  spores ;  it  also 
lessens  the  work  of  spraying,  where  this  is  done.  The  thinning 
of  fruit,  when  abundant,  or  the  removal  of  decayed  specimens, 
is  a  common  practice  that  aids  in  minimizing  most  rot  troubles. 
Greenhouse  men  fight  many  troubles,  as  leaf  spot  of  violet,  by 
picking  off  the  diseased  leaves  as  fast  as  they  appear.  As  many 
of  our  greenhouse  and  garden  troubles  first  get  a  foothold  on 
a  few  leaves,  the  prompt  removal  of  these  is  desirable.  The 
place  for  all  such  refuse  is  the  fire. 

Fungicides.  One  of  the  most  effective  methods  of  fighting 
many  fungous  diseases  is  by  the  use  of  fungicides.  These  are 
prepared  in  such  strengths  that  the  spores  adhering  to  the 
treated  parts  are  either  killed  or  prevented  from  germinating 
while  the  tissues  of  the  plant  are  not  injured.  Such  treatments 
are  made  in  different  ways  to  meet  the  requirements  of  various 


SPRAYING   MIXTURES.  293 

troubles.  Seed  treatment,  for  instance;  where  the  seed  is  soaked 
or  sprinkled  with  the  mixture,  has  been  found  an  effective 
method  for  preventing  most  of  the  cereal  smuts.  Applied  to 
the  tubers  it  is  one  of  the  ways  of  keeping  down  scab  of  potatoes. 
Soil  treatment  is  sometimes  given  where  the  germs  become 
established  in  the  ground,  as  in  the  case  of  onion  smut  and  club 
root,  when  lime  and  sulphur  may  be  used. 

Fungicides  are  most  commonly  applied  as  a  spray.  By  means 
of  spray  pumps,  the  fungicide  is  distributed  uniformly  over  all 
parts  liable  to  infection  as  a  fine  mist.  Upon  drying,  if  the 
fungicide  contains  a  sediment,  this  serves  to  destroy  spores  that 
are  brought  later.  Spraying  depends  largely  for  its  success  on 
preventing  rather  than  curing  disease.  The  man  who  wins  with 
this  treatment  is  the  one  who  anticipates  and  precedes  his  trouble 
rather  than'  the  one  who  follows  along  after  the  disease  has 
gained  a  foothold.  From  the  above  consideration,  it  becomes 
apparent  that  there  are  two  very  important  factors  to  successful 
spraying;  namely,  it  must  be  done  always  with  thoroughness 
and  at  the  proper  time,  which  varies  with  the  disease  to  be 
treated.  A  great  many  substances  have  been  tried  as  fungicides  ; 
a  few  of  the  most  valuable  are  given  here.  Further  informa- 
tion on  this  subject  is  given  in  Reports  1890,  p.  no;  1893,  p. 
103;  1898,  p.  266,  and  Bulletins  in,  115,  125,  142  of  this 
Station. 

Bordeaux  Mixture.  4  lbs.  Copper  Sulphate,  4  lbs.  Fresh 
Lime,  40  to  50  gals.  Water.  Dissolve  the  copper  sulphate  in 
hot  or  cold  water,  suspending  in  a  coarse  bag.  Slake  the 
lime  in  a  small  amount  of  water  and  then  strain  into  the  spray 
barrel  which  is  half  filled  with  water.  Dilute  the  copper  sul- 
phate to  about  half  a  barrel  and  then  pour  into  the  spray  barrel, 
stirring  the  mixture.  If  necessary,  add  a  little  water  to  fill  the 
barrel.  Where  large  quantities  are  used,  it  is  advisable  to  make, 
stock  solutions  of  the  lime  and  the  copper  sulphate,  each  con- 
taining I  lb.  to  I  gal.  of  water.  The  proper  proportions  of  each 
(4  gallons  each  per  barrel)  can  then  be  used,  as  in  the  preceding 
account,  when  needed.  Bordeaux  mixture  is  the  best  fungicide 
and  is  to  be  used  in  all  cases  except  when  sediment  on  the 
sprayed  parts  is  objectionable.  The  home-made  mixture  is  pre- 
ferable to  anything  bought  in  the  market ;  and  the  dry  powders 
used  for  dusting  merit  little  attention  as  yet. 


294        CONNECTICUT    EXPERIMENT    STATION    REPORT^    1 903- 

Dilute  Bordeaux.  2  lbs.  Copper  Sulphate,  4  lbs.  Fresh  Lime, 
40  to  50  gals.  Water.  This  is  sometimes  used  when  there  is 
danger  of  burning  the  foHage  by  use  of  the  stronger  solution, 
as  in  the  case  of  peach  and  Japanese  plums.  Caution,  however, 
may  be  necessary  even  with  this  strength,  especially  on  old 
foliage.  Perhaps  it  is  most  useful  for  the  second  spraying,  when 
necessary  for  peach  curl. 

Resin  Bordeaux.  5  lbs.  Resin,  i  Ib.-Soda  lye,  i  pt.  Fish  Oil, 
5  gals.  Water.  Dissolve  the  resin  in  the  oil  heated  over  fire; 
cool  and  add  the  lye,  stirring  slowly;  then  add  water  and  boil 
until  mixture  will  dissolve  thoroughly  in  cold  water.  Use  at 
rate  of  two  gallons  to  a  barrel  of  Bordeaux.  This  makes  the 
Bordeaux  mixture  adhere  better  to  smooth  foliage  and  also  to 
last  longer.  It  will  probably  be  found  most  efficient  when  used 
on  such  plants  as  carnations,  onions,  asparagus,  etc. 

Soda  Bordeaux,  i  lb.  Soda  lye,  j  lbs.  Copper  Sulphate,  5 
OS.  Lime,  50  gals,  zvater.  Halsted,  of  New  Jersey,  gives  this 
as  a  substitute  for  Bordeaux  when  one  objects  to  much  sediment. 
It  requires  more  care  in  its  preparation,  as  an  excess  of  soda, 
or  too  little,  will  burn  the  foliage,  so  the  formula  calls  for  just 
enough  soda  to  neutralize  the  copper,  with  a  little  lime  added 
to  make  it  slightly  alkaline.  Selby,  of  Ohio,  used  a  slightly 
modified  formula  (4  lbs.  copper  sulphate,  i^  to  1^4  lbs.  soda 
lye,  50  gals,  water),  which  he  preferred  to  Amm.  Sol.  Cop.  Car. 
for  the  late  sprayings  against  black  rot  of  grapes.  His  formula, 
because  of  the  omission  of  lime,  leaves  no  sediment. 

Amm.  Sol.  Cop.  Carbonate.  5  oss.  Copper  Carbonate,  5 
pts.  Ammonia,  //5  gals.  Water.  Dilute  the  ammonia,  if  strong, 
with  several  volumes  of  water  and  use  just  enough  to  dissolve 
the  copper  carbonate;  then  dilute  with  water  to  45  gallons. 
This  fungicide  is  often  used  to  replace  Bordeaux  when  no 
sediment  is  desired  on  the  sprayed  plants.  Because  it  lacks  this 
sediment  its  fungicidal  value  is  temporary  and  it  has  to  be 
used  more  frequently.  There  is  danger  of  burning  the  foliage 
if  the  solution  is  improperly  prepared,  so  care  is  needed  to  use 
just  enough  but  not  too  much  of  the  ammonia.  It  is  most  fre- 
quently used  in  the  later  sprayings  for  bitter  rot  of  apple,  rots  of 
grapes  and  celery  leaf  spots. 

Copper  Sulphate.  3  to  4  lbs.  Copper  Sulphate,  45  gals. 
Water.     This  strength  is  used  as  a  winter  spray,  where  it  is 


SPRAYING    MIXTURES.  295 

desired  to  kill  spores  (or  lichens)  on  the  limbs.  A  weaker 
solution,  I  lb.  to  2^0  gals.,  is  sometimes  advocated  as  a  summer 
spray  for  peach  rot;   but  the  writer  has  not  tried  this  strength. 

Potassium  Sulphide,  j  ozs.  Potassium  Sulphide,  lo  gals. 
Water.  This  fungicide  has  been  found  especially  useful  on  the 
powdery  mildews.  Because  it  leaves  no  sediment,  it  is  also 
adapted  for  greenhouse  work  in  general  but  requires  frequent 
applications.  A  different  strength  has  been  used  for  sprinkling 
grain  to  prevent  smut. 

Formalin.  {A)  i  lb.  (i  pt.)  Formalin,  jo  gals.  Water. 
(B.)  I  lb.'  to  JO  gals.  Water.  The  (A)  formula  is  used  for 
prevention  of  grain  smuts,  by  thoroughly  sprinkling  a  pile  of 
the  grain  which  is  stirred  so  that  all  the  seeds  are  wetted.  The 
grain  is  left  in  piles  or  sacks  over  night  before  drying  or  planting. 
The  (B.)  formula  is  used  for  potato  scab,  the  tubers  being 
soaked  in  it  i^  to  2  hours.  Selby,  of  Ohio,  also  recommends 
its  use  for  onion  smut,  the  seed  being  sprinkled  as  it  lies  in  the 
drills  at  planting. 

Corrosive  Sublimate.  This  is  sometimes  used  instead  of 
formalin  for  grain  smuts  or  potato  scab.  In  the  latter  case  the 
tubers  are  soaked  in  a  solution  i  lb.  to  50  gals,  for  i^  hours. 
This  is  a  poison  and  corrodes  metals,  hence  care  is  needed  in 
its  use. 

Sulphur.  In  the  greenhouse  this  is  used  to  check  the 
powdery  mildews.  Most  frequently  the  powder  is  sprinkled 
over  the  foliage.  Sometimes  the  fumes  produced  by  heating 
are  used,  but  care  should  be  exercised  not  to  ignite  the  sulphur. 
A  better  method  is  to  mix  the  sulphur  with  oil  and  paint  this 
on  the  steam  pipes.  Sulphur  is  also  used,  sometimes  with  lime, 
on  infected  land  to  prevent  onion  smut.  Stewart,  of  New  York, 
recommends  100  lbs.  mixed  with  50  lbs.  air-slaked  lime  per 
acre,  used  in  the  drills  with  the  seed.  / 

Lime.  Occasionally  this  is  put  on  land  infested  with  certain 
fungi.  For  club  root  of  cabbages,  etc.,  80  bushels  per  acre  sown 
broadcast  in  the  fall  is  recommended.  For  onion  smut  75  to 
125  bushels  per  acre  drilled  in  with  a  fertilize'r  drill  are  required. 

Hot  Water.  For  the  grain  smuts,  soaking  the  seed  10  to  15 
minutes  in  hot  water  at  132-5°  F.  is  one  of  the  most  effective 
preventive  treatments.  Where  large  amounts  of  grain  are  to  be 
treated,  the  cumbersomeness  of  the  method  and  the  trouble  in 
drying  the  grain  are  the  chief  objections  against  its  use. 
20 


296      connecticut  experiment  station  report^  ipos- 

Spray  Machinery. 

For  a  general  discussion  of  this  subject  and  illustrations  of 
types  of  pumps,  see  Bulletin  125  of  this  Station,  also  Reports 
1890,  p.  104;  1893,  pp.  74,  105;  1898,  p.  266.  It  is  purposed 
here  merely  to  mention  the  different  kinds  and  indicate  the  field 
in  which  they  are  most  useful. 

Atomisers.  These  are  bellows  that  produce  the  spray  from 
a  small  cup  containing  the  liquid  at  their  tip.  They  are  hard 
to  work  for  any  length  of  time  and  their  usefulness  is  confined 
to  the  greenhouse  or  small  beds  of  ornamental  plants  outdoors. 

Powder  Guns.  These  are  used  to  dust  dry  mixtures  over  the 
surface  of  plants,  usually  when  dew  is  on  them.  They  are  not 
of  much  value  in  fighting  fungi. 

Pail.  Pumps.  The  best  form  is  that  in  which  the  pump  is 
inserted  in  any  pail  and  held  in  place  by  the  foot  while  one 
hand  is  used  to  pump  and  the  other  to  direct  the  spray.  These 
are  of  value  around  gardens  or  with  small  fruit  grown  on  a 
limited  scale.     Effective  pumps  are  likely  to  be  expensive. 

Knapsack  Sprayers.  There  are  two  types ;  those  in  which 
compressed  air  is  first  pumped  into  a  reservoir  and  then  used 
at  will  to  force  out  the  spray,  and  the  common  type  in  which 
the  spray  is  forced  out  directly  by  pumping.  These  are  useful 
on  small  fruit  farms  or  in  gardens  where  one  can  not  use  a 
barrel  pump  mounted  in  a  wagon.  It  is  rather  hard  work  to 
carry  one  of  these  pumps  on  the  b'ack  and  spray  for  any  length 
of  time  and  so  they  are  not  very  popular. 

Barrel  Pumps.  When  one  wishes  to  get  among  plants 
where  there  is  not  room  for  a  wagon,  the  small  barrel  pump 
mounted  on  two  wheels  is  very  handy  and  preferable  to  the 
knapsack  sprayers.  The  ordinary  pump  mounted  in  a  kerosene 
barrel  and  carried  around  in  a  cart  or  light  wagon  is  the  type 
in  most  common  use.  The  style  in  which  the  air  chamber  is 
immersed  in  the  barrel  with  only  the  handle  protruding  is  now 
accepted  as  the  best.  In  purchasing  such  a  pump,  one  should 
select  a  durable  rather  than  a  che^p  make,  and  one  that  is  strong 
enough  to  readily  supply  two  lines  of  hose,  each  with  a  double 
nozzle.  In  commercial  orchards  force  pumps  are  sometimes 
used  in  tanks  of  large  capacity.  For  certain  purposes,  as  potato 
spraying,  an  apparatus  may  be  fitted  up  with  stationary  nozzles. 
See  Report  1893,  p.  75. 


NOTES    ON    PARASITIC    FUNGI.  297 

Power  sprayers.  In  these  machines  the  power  is  other  than 
by  hand.  Steam  is  used  in  some  cases,  but  such  machines  have 
scarcely  obtained  a  foothold  in  this  state.  The  most  common 
type  is  where  the  power  is  supplied  by  the  horses  through 
gearing.  This  makes  it  necessary  to  keep  the  apparatus  moving, 
and  thus  often  prevents  sufficient  spray  reaching  the  plants. 
Recently,  machines  in  which  the  force  is  supplied  by  compressed 
air  or  by  liquid  carbonic  acid  gas  have  been  placed  on  the 
market  and  are  attracting  attention.  As  yet,  a  perfect  and  cheap 
power  sprayer  does  not  seem  to  have  been  developed. 

NOTES  ON  SPECIFIC  TROUBLES. 
The  following  notes  are  upon  the  specific  troubles  that  have 
been  reported  in  this  state.  Most  of  them  have  been  seen  the  past 
two  seasons.  A  few  of  the  hosts,  though  economic,  are  not 
grown  commercially  in  this  state.  Some  of  the  fungi,  while 
occurring  on  cultivated  plants,  are  scarcely  of  economic  import- 
ance. One  can  never  be  sure,  however,  that  these  may  not  at 
some  time  become  troublesome.  The  few  physiological  troubles 
that  are  given  are  distinguished  in  the  headings  by  the  use 
of  italicized  common  names.  Specimens  of  all  have  been  placed 
in  the  Station's  herbarium  and  special  mounts  of  the  most 
important  have  been  made  for  educational  purposes.  The  hosts 
are  arranged  alphabetically. 

ALFALFA,  Medicago  sativa. 
Leaf  Spot,  Pseiidopezisa  Medicaginis  (Lib.)  Sacc.  This  is 
a  common  fungous  trouble  of  alfalfa,  though  not  so  important 
in  this  state  since  the  host,-  apparently,  can  not  be  extensively 
grown  here.  It  shows  as  small  reddish  purple  spots  scattered 
over  the  leaves,  which  finally  become  yellowish.  The  only  time 
the  fungus  has  been  reported  as  injurious  was  by  Sturgis  in 
the  Report  for  1899,  p.  281. 

APPLE,  Pints  Malus. 
Bitter  Rot,  Glomerella  rufomaculans  (Berk.)  Sp.  &  von 
Schr.  Plate  XII,  c.  The  summer  spore  stage  (Glceosporium 
fructigenum)  of  this  fungus  is  responsible  for  serious  injury  to 
apples,  especially  during  recent  years  in  the  middle  west.  In 
Connecticut  it  does  not  seem  to  be  nearly  so  troublesome.     The 


298        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

fruit  often  begins  to  rot,  while  yet  green,  early  in  July,  and  if 
the  season  is  moist  from  then  on  the  trouble  becomes  greatly 
increased,  even  causing  serious  rotting  after  the  apples  are  stored. 
Rotten  sunken  areas  are  formed  which  rapidly  increase  in  size, 
and  in  moist  weather  produce  numerous  pinkish  fruiting  pus- 
tules arranged  in  concentric  circles.  The  spores  are  viscid  and 
so  are  easily  carried  by  insects.  Recently  the  fungus  has  been 
discovered  on  the  branches,  where  it  forms  cankered  areas  often 
at  the  base  of  the  old  fruit  spurs.  It  is  in  these  that  the  myce- 
lium passes  the  winter  and  produces  spores  for  general  infection 
another  year.  The  winter  or  asco-spore  stage  is  saprophytic 
and  curiously  enough  was  observed  in  artificial  cultures  of  the 
fungus  before  found  in  nature.  Besides  the  apple,  this  fungus 
has  the  pear,  and  probably  the  quince,  for  hosts  in  this  state. 
The  treatment  given  for  apple  scab,  coupled  with  the  pruning 
of  diseased  limbs  and  the  gathering  of  rotting  fruit,  is  apparently 
sufficient  for  Connecticut,  but  in  more  southerly  states,  where 
the  trouble  is  often  serious,  the  sprayings  with  Bordeaux  are 
followed  later  in  the  season  with  Amm.  Sol.  Cop.  Carbonate 
(Bulls.  Ill,  p.  5;   142,  p.  2). 

Black  Mold,  Fumago  vagans  Pers.     See  Pear. 

Black  Rot,  Sphaeropsis  M.aloriim  Pk.  Plate  XI,  ^.  One 
of  the  most  common  and  universal  troubles  of  the  apple  is  black 
rot.  Ordinarily  this  does  not  attack  green  fruit,  except  through 
insect  injuries.  It  is  most  troublesome  to  the  summer  varieties 
at  time  of  ripening  and  to  fall  and  winter  varieties  after  storage. 
The  apples  on  rotting  are  brown  at  first,  but  usually  blacken 
later,  hence  the  common  name.  This  fungus  also  occurs  on 
the  limbs,  forming  depressed,  reddish,  dead  areas,  or  it  may 
kill  the  young  twigs  by  girdling.  It  is  very  common  on  the 
leaves,  forming  roundish  or  irregular  reddish  brown  spots ;  and 
in  this  state  most  of  the  apple  leaf  spot  troubles  seem  to  be 
caused  by  it.  So  far  only  one  spore  stage  has  been  found,  and 
this  places  it  with  the  imperfect  fungi.  The  fruiting  stage 
shows  on  the  twigs  as  small  black  pustules,  easily  seen  by  the 
naked  eye.  The  pear  and  quince  are  other  hosts  of  the  fungus. 
To  fight  this  trouble,  the  trees  should  be  thoroughly  pruned 
of  all  dead  limbs  and  twigs ;  the  larger  cankered  areas,  when 
found,  should  be  scraped  and  painted ;  the  trees  should  be 
given  a  winter  spraying,  followed  by  the  ordinary  treatment  for 
scab.     (Rep.  1893,  p.  91 ;   Bull.  142,  p.  2.) 


NOTES    ON    PARASITIC    FUNGI.  299 

Blue  Mold^  PenicilUum  glaucum,  Lk.  This  common  sapro- 
phytic mold  occasionally  causes  rot  in  storage  apples.  In  a 
fruiting  condition  it  is  easily  identified  by  the  green  blue  spores 
that  appear  in  clusters  on  the  surface  of  the  rotten  fruit. 

Brown  Rot_,  Sclerotinia  fructigena  (Pers.)  Schrt.  Occa- 
sionally this  causes  rotting  of  ripe  apples.  It  does  not  seem 
to  be  specifically  different  from  the  brown  rot  of  peach,  q.  v. 

Crown  Gall.  The  crown  galls  on  the  apple  have  about  the 
same  appearance  as  those  on  the  peach  and  plum,  though  it  is  not 
yet  definitely  known  if  they  have  the  same  cause.  They  form 
irregular  knots  or  swellings  at  the  crown  or  more  commonly 
lower  down  on  the  roots.  So  far,  in  this  state,  the  trouble  has 
been  seen  only  on  young  trees,  chiefly  nursery  stock.  There 
is  some  question  just  what  the  later  effect  is  on  the  tree,  but 
it  is  safest  to  reject  all  stock  showing  any  signs  of  this  trouble. 
In  1899,  Dr.  Sturgis  set  out  on  the  Station  grounds  ten  young 
trees  affected  with  knot;  part  of  these  had  the  knots  cut  off, 
others  had  knots  cut  off  and  roots  then  treated  with  copper 
sulphate,  and  some  were  left  with  knots  on.  After  three  seasons 
of  growth,  these  trees  were  dug  by  the  writer  and  the  roots 
carefully  examined.  Very  little  difference  could  be  seen  in  any 
of  the  trees  at  this  time  and  the  knots  had  spread  very  little, 
if  any.     (See  Report  Conn.  Pom.  Soc.  1903,  p.  43.) 

European  Canker,  Nectria  difissima  Tul.  Plate  XII,  d. 
This  is  found  usually  on  old  and  neglected  trees,  where  it  gets 
started  in  the  branches  through  wounds  or  possibly  through 
winter  killing.  As  it  is  perennial  through  its  mycelium,  the 
bark  is  prevented  each  year  from  forming  over  the  wound,  so 
that  an  enlarging  canker  is  formed  showing  the  annual  layers 
of  wood  in  concentric  rings  around  the  original  starting  point. 
If  examined  at  the  proper  time  with  a  hand  lens,  the  small, 
red,  globular  fruiting  bodies  of  this  sac  fungus  can  be  seen 
clustered  on  the  edges  of  the  cankered  area.  All  cankered  limbs 
should  be  removed  and  the  larger  cut  surfaces  be  given  a  coat 
of  paint. 

Fly  Speck,  Leptothyrlmn  Ponii  (Mont.  &  Fr.)  Sacc.  Plate 
XI,  d.  The  small  black  spots,  similar  to  fly  specks,  produced 
by  this  fungus  are  usually  clustered  on  the  fruit  in  numbers 
from  half  a  dozen  to  a  hundred  or  more.  The  conditions  favor- 
able for  sooty  blotch  also  produce  this  fungus,  so  the  two  are 


300        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

often  found  together.  The  former  trouble,  however,  proves  to 
be  the  more  serious  as  it  is  more  abundant  and  evident.  So  far 
the  writer  has  not  found  the  fly  speck  fungus  in  a  fruiting 
condition,  though  it  is  classified  with  the  sac  fungi.  A  similar 
fungus  was  sent  to  the  Station  on  peach  twigs  in  a  fruiting 
condition,  last  year,  so  it  is  not  unlikely  that  this  fungus  winters 
on  the  apple  twigs.  • 

Leaf  Spots,  Phyllosticta  sps.  Not  unfrequently  one  finds 
species  of  the  Phyllosticta  fungi  on  the  round  brown  spots  on 
apple  leaves  and  apparently  the  primary  cause  of  these.  As 
stated  before,  most  of  these  leaf  spots  are  caused  by  the  black 
rot  fungus.  The  fruiting  stages  of  the  two  fungi  are  often 
found  in  the  same  spot.  At  yet  little  is  known  of  the  life  his- 
tory of  these  Phyllosticta  fungi,  but  they  are  possibly  summer 
stages  of  sac  fungi. 

Pink  Mold,  Cephalothecmm  roseum  Cda.  During  the  fall 
of  1902,  this  fungus,  which  commonly  occurs  only  on  decaying 
vegetation,  caused  very  serious  loss  to  the  apple  growers  of  New 
York  state  and  to  a  less  extent  in  this  state.  The  trouble  devel-, 
oped  after  the  apples  were  picked  for  storage.  Its  development 
was  the  direct  result  of  badly  scabbed  apples,  and  a  wet  fall, 
since  it  was  only  through  the  scabby  spots  that  the  mold  gained 
entrance  to  the  fruit.  These  spots  became  covered  with  a  lux- 
uriant white  growth  of  mycelial  threads,  which  on  producing 
the  spores  changed  to  a  pinkish  color.  The  mycelium  also 
penetrated  the  tissues  and  caused  the  rot  of  the  apple.  Cold 
storage  checked  the  trouble  but  did  not  prevent  the  rotting  of 
the  apples  when  again  brought  into  a  warm  atmosphere.  The 
prevention  of  this  trouble  requires  a  treatment  that  goes  back 
to  the  prevention  of  scab. 

Powdery  Mildew,  PodosphcBra  leucotricha  (Ell.  &  Ev.) 
Salm.  This  is  usually  a  pest  only  in  nurseries,  though  occa- 
sionally found  in  orchards  on  sprouts  at  the  base  of  the  trees. 
It  forms  a  cobweb-like  growth  on  the  leaves  and  on  the  young 
twigs  a  dirty  whitish  felt,  within  which  are  embedded  the  small 
brownish  spherical  receptacles  of  the  asco-spores.  It  thrives 
best  in  nurseries  where  the  blocks  of  trees  are  very  closely 
planted,  and  may  be  avoided  by  thinner  planting  and  spraying 
with  potassium  sulphide  or  Bordeaux  mixture. 


NOTES   ON    PARASITIC    FUNGI.  3OI 

RusTS^  Gym7io Sporangium  macropus  Lk.,  G.  glohosum  Farl. 
Plate  XI,  c,  Colortype  2.  Two  rusts,  similar  in  appearance, 
occur  here  on  the  apple  leaves,  the  former  apparently  the  more 
abundantly.  The  apple  stages  {Rcestelia  pirata  and  R.  lacerata) 
are  the  I  or  cluster  cup  stages  of  the  mature  forms  which  occur 
as  "Cedar  apples"  on  cedar  trees  in  late  April  to  June.  Infec- 
tion of  the  apple  leaves  takes  place  in  May  or  June,  producing 
bright  orange-colored  spots  that  begin  to  show  prominently  in 
July.  The  fringed  cluster  cups  [Plate  XI,  c]  appear  on  the 
under  surface  of  these  the  latter  part  of  July  and  August,  and 
their  spores  carry  the  fungus  back  to  the  young  cedar  twigs 
for  new  infection.  There  is  great  difference  in  the  susceptibility 
of  different  varieties  of  apple  to  the  attack  of  these  fungi.  One 
often  sees  certain  varieties  of  trees  in  the  orchard  and  nursery 
badly  infected  while  others  are  free.  Selection  of  varieties, 
therefore,  is  one  way  of  avoiding  the  trouble.  Wealthy  and 
Fallowater,  apparently,  rust  badly.  Cedar  trees  in  the  vicinity 
of  the  orchard  should  be  cut  down.  Spraying,  as  yet,  seems 
to  have  given  poor  results.     [Rep.  1891,  p.  161 ;  Bull.  142,  p.  2.] 

Scab,  Venturia  inceqiiaUs  (Cke.)  Aderh.  Plate  XII,  a-b. 
One  of  the  fungi  most  widely  discussed  is  the  apple  scab.  This 
is  partly  due  to  its  general  distribution  and  its  injurious  nature, 
but  also  to  the  fact  that  it  was  one  of  the  first  whose  control 
was  attempted  by  the  use  of  fungicides.  It  occurs  commonly 
on  the  fruit  and  leaves ;  very  rarely  on  the  twigs.  On  the 
fruit  it  produces  superficial  olive-black  "scabby"  spots,  that 
often  cause  the  young  fruit  to  become  one-sided  and  stunted. 
Scabby  fruit,  also,  is  apt  to  wait  in  storage  and  become  rotten 
through  infection  with  other  fungi  (see  pink  mold).  On  the 
leaves  the  scab  colonies,  one-quarter  to  one-third  of  an  inch  in 
diameter,  are  shown  by  a  hand  lens  to  consist  of  superficial 
fertile  threads  radiating  out  from  a  common  center.  The  only 
specimens  found  on  twigs  [Plate  XII,  b]  showed  small  pustules 
not  unlike  those  of  the  black  rot  fungus.  Apple  scab  is  the 
parasitic  summer  stage  {Fusicladium  dendriticum)  of  a  sac 
fungus  that  develops  as  a  saprophyte  on  the  fallen  leaves  during 
the  fall  and  winter,  maturing  its  spores  in  early  spring  in  time 
for  infection  of  the  unfolding  leaves.  Spraying  experiments 
have  shown  that  this  trouble  can  be  controlled  by  Bordeaux 
mixture.     The  first  treatment  is  given  on  the  unfolding  leaves 


3G2        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

before  the  blossoms  open,  the  second  just  after  the  petals  fall, 
and  the  third,  if  necessary,  follows  two  or  three  weeks  later. 
Sometimes  a  winter  treatment  with  copper  sulphate  is  given  on 
the  dormant  wood,  but  this  is  hardly  necessary.  [Rep.  1893,  pp. 
^2,  88;   Bull.  142,  p.  2.] 

Sooty  Blotch,  f  Phyllachora  pomigena  (Schw.)  Sacc.  Plate 
XI,  b.  During  the  past  two  seasons  this  has  been  one  of 
our  most  serious  apple  pests.  The  fungus  forms  a  prostrate 
growth  of  matted  threads,  that  in  olive-black  colonies  more  or 
less  cover  the  surface  of  the  fruit.  Because  of  its  superficial 
growth  the  fungus  thrives  best  under  moist  conditions,  such  as 
the  past  two  seasons  have  afforded.  It  attracts  most  attention 
on  the  lighter  skin  varieties,  as  the  Greening,  because  of  the 
contrast  in  color.  The  injury  to  the  fruit,  at  first,  is  chiefly 
in  its  appearance,  but  this  is  sufficient  to  greatly  affect  the 
market  value.  Later,  ill  effects  are  shown  in  the  keeping  quali- 
ties, as  badly  spotted  fruit  wilts  badly,  because  of  the  rupture 
of  the  cuticle  covering  the  apple,  and  not  infrequently  rotting, 
from  other  fungi,  develops.  So  far  the  writer  has  not  found 
the  mycelium  on  these  blotches  producing  spores,  though  apples 
were  kept  out  doors  over  winter  for  this  purpose.  The  fungus, 
however,  probably  belongs  with  the  sac  fungi.  It  occurs  less 
prominently  on  the  pear.  The  treatment  ordinarily  given  for 
apple  scab  proves  beneficial  in  keeping  this  trouble  in  check.  To 
be  most  effective,  the  third  spraying  should  be  given  when  the 
fruit  has  attained  considerable  size.  [Rep.  1897,  p.  171 ;  Bull. 
142,  p.  2.] 

Baldwin  Spot.  This  trouble  shows  first  in  the  fall  as  small 
sunken  rotten  spots  on  the  Surface  of  the  fruit  and  later  as 
isolated  brown  spots  within  the  flesh,  the  tissue  in  these  often 
collapsing.  When  first  studied  it  was  thought  that  fungi  or 
bacteria  might  be  responsible,  but  now  it  is  generally  considered 
a  physiological  trouble,  possibly  resulting  from  too  great  loss 
of  water  at  these  places.  The  trouble  increases  after  storage, 
especially  in  the  development  of  the  internal  spots.  Very  similar 
spots  have  been  found  in  the  interior  of  potatoes,  which  probably  ' 
result  from  similar  causes  and  conditions.  During  the  past  sea- 
son Baldwin  spot  was  more  prevalent  than  usual,  being  common 
in  Baldwins  especially.  The  poor  condition  of  apples,  induced 
by  the  peculiar  growing  season,   and  by  the   September  gale 


NOTES    ON    PARASITIC    FUNGI.  3O3 

which  shook  most  of  the  fruit  from  the  trees,  may  possibly 
explain  its  greater  prevalence. 

Fruit  Scald.  This  is  a  more  serious  trouble  with  cold  storage 
apples  than  with  those  stored  in  the  ordinary  way.  It  shows  as 
large  brownish  scalded  places  at  first  on  the  skin,  but  eventually 
penetrating  deeper  and  is  usually  most  prominent  on  fair  skin 
varieties.  While  the  cold  no  doubt  has  much  to  do  with 
developing  this  trouble,  it  also  seems  certain  that  the  condition 
of  the  apples  as  they  enter  storage  is  a  very  important  factor. 
It  is  a  trouble  that  is  under  investigation  by  our  government 
pomologists. 

Spray  Injury.  Injury  to  the  foliage  and  the  fruit  often  fol- 
lows spraying  with  Bordeaux  mixture,  especially  when  combined 
with  insecticides.  Circular  brown  spots  are  produced  on  the 
leaves  very  similar  to  those  caused  by  the  leaf  spot  fungi  and 
if  the  injury  is  sufficient  many  of  these  leaves  are  shed  pre- 
maturely. The  injury  to  the  fruit  shows  as  russeting,  and 
may  cause  lop-sided  growth.  Carelessness  in  preparing  the  Bor- 
deaux, failing  to  properly  neutralize  the  copper  sulphate  with 
fresh  lime,  is  sometimes  responsible  for  these  injuries.  In  wet 
seasons,  injury  sometimes  results  where  proper  precautions  have 
been  taken.  As  a  rule,  the  earliest  sprayings  on  the  undeveloped 
leaves  do  not  seem  to  cause  injury  so  frequently  as  later  spray- 
ings on  the  fully  matured  leaves. 

Winter  Injury.  Plates  IX,  a-b,  X,  b,.  As  stated  in  the 
introduction,  many  apple  trees  were  severely  injured  by  the 
sudden  zero  weather  of  December  9,  1902.  This  was  due  to 
the  sudden  change  following  an  open  fall  in  which  the  trees 
had  not  properl}^  matured  for  winter'  conditions.  The  winter 
of  1903-4  has  also  been  a  ver}^  severe  one,  but  the  trees  were 
in  better  shape  for  it.  The  injury  in  1902  was  shown  in  two 
ways.  First:  In  the  nursery  or  very  young  orchard,  especially 
where  the  trees  were  cultivated  late  and  thereby  taken  into 
winter  in  an  unripe  condition,  the  injury  was  confined  principally 
to  the  wood,  the  bark  and  the  cambium  remaining  uninjured. 
This  injury  became  evident  only  on  cutting  across  the  stem,  when 
the  wood  [Plate  X,  b]  showed  a  darker  color  than  normal. 
When  these  trees  were  transplanted  the  following  spring,  the 
unfavorable  conditions  of  a  dry  May  and  a  wet  June  finished 
the  career  of  many.     When  left  in  the  nursery  and  severely 


304        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O3. 

pruned  back  they  made  a  more  or  less  satisfactory  growth  accord- 
ing to  the  severity  of  the  injury.  This  new  growth  of  wood 
showed  as  a  white  ring  in  striking  contrast  to  the  injured  dark 
wood  within.  See  Plate  X.  If  the  old  wood  was  severely 
injured,  even  if  the  new  wood  grew  fairly  well,  there  was  fre- 
quently developed  an  evident  whitish  fungous  growth  at  the 
pruned  surfaces  on  the  injured  wood,  showing  that  there  was 
trouble  ahead  from  wood  rot.  Badly  injured  trees,  too,  were 
very  brittle  and  easily  broken  off.  Second:  In  orchards,  most 
commonly  on  trees  four  to  eight  years  old,  the  injury  often 
showed  as  dead  areas  in  the  bark,  usually  at  the  base  of  the  tree 
and  more  frequently  on  the  northerly  exposures.  Sometimes 
these  sunken  areas  completely  girdled  the  tree,  thereby  finishing 
its  career ;  again  they  extended  a  foot  or  two  up  one  side,  being 
separated  by  a  fissure  from  the  healthy  bark.  Trees  injured 
severely  in  this  way  put  out  an  abundance  of  healthy  foliage 
early  in  the  season  and  appeared  in  normal  health  until  July, 
when  the  leaves  began  to  drop.  Plate  IX,  a,  shows  a  young 
tree  in  Mr.  Gold's  orchard  at  West  Cornwall,  photographed 
in  July,  1902,  that  was  losing  its  foliage  because  of  a  similar 
injury  to  the  base  of  the  tree.  These  dead  areas  resemble 
cankered  spots,  and  the  writer  mistook,  at  first,  the  injury  at 
West  Cornwall  for  a  fungous  trouble,  since  on  some  of  the  dead 
areas  the  fruiting  pustules  of  a  fungus  [Plate  IX,  b]  were  found. 
Evidently  these  were  developing  as  a  later  and  saprophytic 
growth.  The  healthy  bark  with  its  lenticels,  which  are  some- 
times mistaken  for  fungous  growths,  is  shown  in  Plate  IX,  c. 
Sun  scald  is  also  a  winter  injury  of  the  bark  due  to  warm 
weather,  starting  into  activity  the  tissues  on  southerly  exposures 
of  the  trunk,  followed  by  a  sudden  freeze. 

ASH,  Fraxinus  sps. 

Leaf  Speck,  Piggotia  Fraxini  B.  &  C.  This  produces  very 
small  black  fruiting  pustules  on  the  under  surface  of  the  leaves 
of  white  ash. 

Rust,  ^^cidimn  Fraxini  Schw.  This  rust  forms  its  cluster 
cups  on  the  leaves  and  their  petioles  in  July  and  August.  Often 
it  produces  considerable  distortion  of  the  petioles  where  these 
spore  cups  are  embedded.  It  was  observed  on  the  white  ash, 
F~.  Americana. 


NOTES   ON    PARASITIC    FUNGI.  305 

ASPARAGUS,  Asparagus  officinalis. 

Anthracnose^  F'usarium  sp.  This  trouble  is  sometimes  asso- 
ciated with  the  rust  on  asparagus  stems.  It  causes  light- 
colored  areas  that  become  dotted  with  numerous  pink  pustules 
of  the  spores.  The  tissue  is  killed  at  these  places  and  so  where 
abundant  the  fungus  may  cause  considerable  injury. 

Leopard  Spot.  Apparently  this  is  the  result  of  some  fungus, 
though  it  has  not  been  found  in  a  fruiting  condition.  It  pro'- 
duces  reddish  brown  spots  usually  with  a  distinct  border. 

RusT_,  Puccinia  Asparagi  DC.  By  far  the  most  serious  fun- 
gous pest  of  asparagus,  however,  is  the  rust.  This  shows  as 
dark  red  or  black  pustules  breaking  through  the  skin  on  any 
part  of  the  plant.  These  small  pustules  are  usually  oval  in 
shape,  though  they  may  become  more  elongated,  especially  on 
the  larger  branches.  The  reddish  color  indicates  the  formation 
of  the  uredo-  or  summer  spores,  while  the  black  color  shows  the 
presence  of  the  teleuto-  or  winter  spores.  These  different  spores 
may  even  occur  in  the  same  pustules ;  they  are  most  abundant 
from  August  to  October.  The  cluster  cup  stage  appears  as 
early  as  June,  but  does  little  damage  and  so  far  has  not  been 
observed  by  the  writer.  During  the  past  season  the  rust  was 
later  than  usual  in  appearing  and  consequently  less  destructive. 
Some  growers  in  Connecticut  are  now  spraying  against  this 
trouble,  but  the  work  to  be  effective  must  be  done  thoroughly 
and  repeatedly.  Resin  Bordeaux  seems  to  be  the  best  fungicide 
for  this  purpose  because  of  its  sticking  qualities.  Spraying 
should  begin  the  latter  part  of  July  and  be  continued  until  the 
middle  of  September.  Sometimes  the  dead  fields  in  the  fall  are 
burned  over  to  kill  off  at  least  some  of  the  spores.  According 
to  some  growers  the  Palmetto  is  more  exempt  from  rust  than 
most  of  the  varieties.     [Rep,  1896,  p.  281 ;  Bull.  142,  p.  3.] 

ASTER,  Callistephus  hortensis. 

•Rust,  Coleosporium  Sonchi-arvensis  (Pers.)  Lev.  This  rust 
has  been  found  so  far  only  sparingly  on  cultivated  asters.  In 
nature  it  is  very  common  on  wild  asters  and  goldenrods.  The 
bright  orange  uredo  pustules  appear  in  clusters  on  the  under 
surface  of  the  leaves. 

Stem  Rot,  Ftisarium  sp?     Some  of  our  growers  report  as 


306        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

serious  a  stem  rot  or  decay  at  the  base  of  asters.  This  is  prob- 
ably caused  by  a  Fusarium  fungus,  though  no  special  study  was 
made  of  this  trouble,  which  evidently  becomes  established  in 
the  soil. 

Yellows.  Apparently  this  is  a  physiological  disease,  which 
may  be  similar  to  peach  yellows.  Affected  plants  are  often 
spindling  with  some  yellowish  or  whitish  foliage  and  usually 
develop  one-sided  flowers  imperfect  in  shape  and  color.  Some 
growers  think  that  the  trouble  becomes  worse  on  ground  used 
year  after  year. 

AZALEA,  Azalea  sp. 

Rust,  Pucciniastrum  Vacciniorum  (Lk.)  Diet.  The  uredo 
stage  of  this  rust  was  seen  in  a  local  nursery  doing  considerable 
injury  to  certain  cultivated  azaleas,  apparently  native  varieties. 
The  rust  showed  on  the  under  surface  of  the  leaves  as  very 
small  thickly  crowded  orange  dots,  while  the  upper  surface  was 
somewhat  discolored  by  the  injury  to  the  tissues. 

BAEBEERY,  Berberis  sps. 

Anthracnose,  Gloeosporium  Berberidis  Cke.  In  midsum- 
mer barberry  leaves  are  often  found  showing  at  their  tip  or 
margin  dead  areas  which  in  time  may  involve  the  entire  leaf. 
These  brown  "tip  burns"  are  separated  from  the  healthy  green 
tissue  by  a  distinct  purplish  border.  The  very  small  fruiting 
pustules  can  sometimes  be  made  out,  on  the  underside  near  the 
healthy  tissue,  by  aid  of  a  lens. 

Rust,  Puccinia  graminis  Pers.  The  cluster  cup  stage  of  the 
common  black  stem  rust  of  cereals  occurs  on  both  the  wild  and 
cultivated  barberry.  This  appears  in  May  embedded  in  slightly 
swollen  clusters  on  the  undersides  of  the  leaves.     See  Oats. 

BARLEY,  Hordemn  sps. 

Powdery  Mildew,  Erysiphe  graminis  DC.  The  conidial 
stage  (Oidimn  monilioides)  of  this  mildew  occurs  on  the  leaves 
in  greyish  moldy  tufts,  causing  discoloration  of  the  tissues. 

Rusts,  Puccinia  graminis  Pers.,  P.  rubigo-vera  (DC.)  Wint. 
These  common  rusts  cause  considerable  damage  to  barley  raised 
for  green  fodder.     See  Oats. 

Smuts,  Ustilago  nnda   (Jens.)   Kell.  &  Sw.     Plate  XIII,  a. 


NOTES    ON    PARASITIC    FUNGI.  3O7 

The  loose  smut  is  not  uncommon  in  the  spikelets  of  barley, 
changing  them  into  dusty  olive-black  spore  masses.  The 
covered  smut  (U.  Hordei  (Pers.)  Kell.  &  Sw.),  which  has  a 
firmer  blacker  spore  mass,  has  been  seen  but  once.  These 
troubles  may  be  prevented  by  the  modified  hot  water  treatment 
of  the  seed. 

BEANS:   STRING,  Phaseohis  vulgaris;  LIMA,  P.  lunatus. 

Anthracnose,  Colletotrichum  Lindennithianiiin  (Sacc.  & 
Magn.)  Bri.  &  Cav.  Plate  XIII,  c.  This  is  a  common  trouble 
of  beans.  It  occurs  on  both  the  pods  and  the  leaves,  producing 
on  the  former  evident  subcircular  spots  with  a  distinct  reddish 
purple  border.  The  bacterial  trouble  described  later  seems  to 
be  more  common  on  the  leaves  than  this,  and  most  of  the  spots 
examined  on  bean  leaves  have  been  due  to  that.  Anthracnose 
often  gets  started  through  infested  seed ;  so  only  sound  plump 
seed  should  be  used.  Destroying  infected  seedlings  and  the 
first  diseased  leaves  should  prove  helpful  in  checking  its  appear- 
ance. Spraying  with  Bordeaux  should  begin  when  the  plants 
are  only  a  few  inches  high  and  be  continued  at  intervals  of  two 
or  three  weeks  until  the  pods  are  maturing.  Burning  the  rubbish 
at  the  end  of  the  season  is  recommended,  since  the  trouble  is 
probably  carried  by  this  in  the  soil.     [Bull.  142,  p.  3.] 

Blight,,  Pseudomonas  Phaseoli  Smith.  Plate  XIII,  d.  This 
is  very  common  on  the  leaves  of  string  beans,  producing  brown 
dead  areas  at  the  tip  or  margin  or  large  irregular  spots  within, 
the  leaf  often  turning  yellowish  all  over  and  dying.  Parts  of 
these  diseased  areas  often  have  a  pellucid  or  water  appearance. 
On  the  lima  bean  leaves,  one  often  finds  smaller  reddish  bordered 
spots  distinct  from  the  above  and  similar  in  appearance  to  those 
of  anthracnose ;  yet  even  these  seem  to  be  of  bacterial  origin, 
probably  started  by  insect  punctures.  See  note  by  Sturgis  in 
Report  1898,  p.  262.  The  treatment  for  blight  is  the  same  as 
for  anthracnose.     [Bull.  142,  p.  4.] 

Downy  Mildew,  Phytophthora  Phaseoli  Thaxt.  Plate 
XIII,  b,  Colortype  12.  This  fungus  was  first  described  from 
specimens  found  near  New  Haven  by  Professor  Thaxter  in 
1889.  It  occurs  only  on  the  lima  bean  and  has  since  been  found 
in  a  few  other  eastern  states.  It  occurs  most  commonly  on 
the  pods,  covering  them  more  or  less  completely  with  a  con- 


308        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

spicuous  white  felt  of  the  myceHum  and  summer  spore  stage. 
This  distorts  and  often  aborts  the  pods,  rendering  them  unfit  for 
the  market.  Less  commonly  the  fungus  attacks  the  flowers 
and  young  leaves  and  stems.  It  is  most  prevalent  in  moist 
seasons  and  in  the  low  wet  places  in  the  fields.  Too  close  plant- 
ing of  the  vines  also  induces  its  development.  Just  how  the 
fungus  passes  the  winter  still  remains  a  mystery,  as  the  winter 
or  oospores  have  never  been  found,  though  looked  for  carefully 
by  the  writer  and  others.  Probably  the  mycelium  gains  entrance 
to  some  of  the  seeds  and  it  is  carried  over  this  way.  Wet,  low 
land  should  not  be  used  and  the  plants  should  stand  far 
enough  apart  to  admit  plenty  of  sunshine.  Spraying  every 
two  or  three  weeks  from  the  last  of  June  until  September 
is  helpful  in  controlling  the  trouble.  The  first  sprayings  may 
be  made  with  Bordeaux  and  the  later  with  Amm.  Sol.  Cop. 
Carbonate.  The  diseased  pods  should  be  gathered  at  each  pick- 
ing. [Reps.  1889,  p.  167;  1890,  p.  97;  1893,  p.  -jy;  1897, 
p.  159;   1898,  p.  236;   Bull.  142,  p.  4.] 

Leaf  Blotch,  Isariopsis  griseola  Sacc.  (Cercospora  colum- 
nar e  E.  &  E. )  In  one  field  this  was  found  abundant,  producing 
angular  brownish  areas  of  varying  size  and  giving  the  leaves 
a  sickly  yellowish  color.  With  a  lens  the  fruiting  stage  can 
be  seen,  as  small  black  columns  with  greyish  bushy  heads,  stand- 
ing out  on  the  under  surface  of  the  leaves.  It  was  also  found 
on  the  old  pods. 

Leaf  Spot,  Phyllosticta  phaseolina  Sacc.  This  was  seen 
once.  It  produces  large  dark  spots  showing  concentric 
markings. 

Mold,  Fusariuni  sp.  If  beans  are  left  too  long  in  the  field 
in  the  fall  or  if  not  properly  matured  when  stored,  this  fungus 
develops  a  vigorous  growth  of  white  mycelium  over  and  in  the 
seeds. 

Rust,  Uromyces  appendicnlafus  (Pers.)  Lk.  Plate  XIII,  e. 
This  is  very  injurious  to  some  varieties,  including  both  dwarf 
and  pole  forms  of  the  string  beans.  The  small,  roundish,  dusty, 
reddish  black  pustules  that  usually  thickly  cover  either  surface 
of  the  leaves  contain  the  uredo-  and  teleuto-spores.  These 
occur  occasionally  on  the  pods.  The  rust  is  most  common  in 
August  and  September.  Avoid  planting  varieties  that  rust 
badly,  and  burn  the  rubbish  in  the  fall.     [Bull.  142,  p.  4.] 


NOTES    ON    PARASITIC    FUNGI.  309 

BEET,  Beta  vulgaris. 

Leaf  Blight,  Cercospora  beticola  Sacc.  Plate  XIV,  a. 
This  is  a  very  common  trouble  on  beets  and  chard.  The  leaves 
are  more  or  less  covered  with  roundish  spots,  one-sixteenth  to 
one-quarter  inch  in  diameter,  which  have  a  greyish  center  and 
a  purplish  border.  Only  summer  spores  are  known,  placing  it 
with  the  imperfect  fungi. 

Scab,  Oospora  scabies  Thaxt.  This  causes  scabby  spots  on 
the  roots  similar  to  .those  on  potatoes.  In  an  experiment, 
Sturgis  found  that  "beets,  mangels,  turnips  and  ruta-bagas  are 
susceptible  to  potato  scab  in  a  marked  degree  if  planted  on  soil 
infested  with  the  fungus  causing  that  disease.  None  of  these 
root  crops,  therefore,  should  occupy  land  which  has  recently 
borne  scabby  potatoes."     [Rep.  1896,  p.  266.] 

BLACKBEKRY,  Riibiis  villosus  and  vars. 

Crown  Gall,  ?  Dendrophagiis  globosiis  Toum.  Reported  on 
this  host  but  not  seen  by  writer.     See  Raspberry. 

Leaf  Spot,  Septoria  Riibi  Westd.  Plate  XIV,  b.  This  is  a 
common  trouble  on  the  foliage,  producing  small,  circular  spots 
that  eventually  have  a  whitish  center  with  a  purple  border.  The 
fruiting  pustules  when  present  show  as  minute  black  dots  sunken 
in  the  white  area.  It  is  caused  by  one  of  the  imperfect  fungi 
and  occurs  also  on  the  raspberry  and  dewberry.  It  is  ques- 
tionable just  how  much  damage  this  causes  when  fairly  abun- 
dant, but  if  it  proves  serious,  early  spraying  with  Bordeaux 
would  probably  pay.     [Bull.  142,  p.  4.] 

Orange  Rust,  Gymnoconia  interstitialis  (Schl.)  Lagerh. 
Plate  XIV,  c,  Colortype  9.  This  forms  orange  colored  dusty 
outbreaks  thickly  covering  the  under  surface  of  the  leaves  from 
May  to  July.  At  first  these  are  covered  by  the  epidermis,  upon 
the  rupture  of  which  the  spores  are  gradually  scattered.  Orange 
rust  {Cceoma  nitens)  is  the  I  stage  of  the  mature  form  III,  or 
teleutal,  which  occurs  later  in  very  inconspicuous  pustules  on 
the  same  plants.  The  mycelium  is  perennial  in  the  underground 
parts  of  the  host,  so  that  shoots  year  after  year  from  these  will 
be  rusted.  The  best  remedy  is  to  dig  up  and  destroy  the  infected 
plants  as  soon  as  discovered ;  it  is  especially  desirable  to  remove 
them  early  in  the  spring  before  the  spore  pustules  break  open. 
Certain  varieties  seem  more  subject  to  this  trouble  than  are 


3IO        CONNECTICUT    EXPERIMENT    STATION    REPORT,    1903- 

others,  and  it  also  occurs  on  the  raspberry  and  dewberry  and 
on  wild  plants  of  all  of  these.  It  is  well  to  see  that  none  of 
the  latter  flourish  in  the  vicinity  of  the  cultivated  plants.  [Rep. 
1889,  p.  172;   Bull.  142,  p.  4.] 

BLUE  GRASS,  Poa  pratensis. 

Powdery  Mildew,  Erysiphe  graminis  DC.  The  conidial 
stage  of  this  mildew  often  occurs  on  uncut  grass  in  fence  rows, 
etc.  It  forms  a  white  powdery  coating  on  portions  of  the 
leaves. 

BOX  ELDER,  Negundo  aceroides. 
Leaf  Spot,  Phyllosticta  minima  (B.  &  C.)  Ell.     See  Maple. 

BROME  GRASS,  Bromus  inermis. 

Ergot,  Claviceps  pvirpurea  Tul.  Collected  once  on  this  and 
several  times  on  other  species  of  Bromus;  sclerotia  smaller  than 
on  rye,  q.  v. 

BROOM  CORN,  Sorghum  vulgare  var. 

Grain  Smut,  Sphacelotheca  Sorghi  (Lk.)  Clint.  Collected 
in  Experiment  Station  grounds.     See  Sorghum. 

BTJCKWHEAT,  Fagopyrum  esculenhim. 

Leaf  Blight,  Ramularia  rufomaculans  Pk.  Plate  XIV,  d. 
Occasionally  this  becomes  abundant  and  injurious  in  buckwheat 
fields,  but  usually  it  is  found  only  sparingly.  Its  fruiting  stage 
forms  whitish,  mealy  growths  scattered  in  patches  over  the 
under  surface  of  the  leaves.  This  summer  spore  stage  is  the 
only  one  known.     [Rep.  1890,  p.  98.] 

Leaf  Spot,  Ascochyta  sp.  Another  trouble  occasionally 
found  on  the  leaves  produces  circular,  reddish  brown  spots. 
These  and  the  fungus  causing  them  are  very  similar,  if  not  the 
same  as  the  leaf  spot  of  Rhubarb. 

CABBAGE,  Brassica  oleracea. 

Club  Root,  Plasmodiophora  BrassiccE  Wor.  Plate  XV,  a. 
This  forms  gall-like  enlargements  on  the  roots.  These  are  mor- 
bid growth  of  plant  tissue,  the  cells  of  which  are  filled  with  the 
spores,    etc.,    of   the    slime   mold    that   produces    the    trouble. 


NOTES   ON    PARASITIC    FUNGI.  3 II 

Eventually  the  infected  tissues  rot,  through  the  action  of  bac- 
teria, and  liberate  these  germs  in  the  soil.  Badly  infected  plants 
have  little  root  hold  in  the  soil  and  so  are  cut  off  from  gathering 
sufficient  plant  food.  They  become  spindling  and  head  out 
poorly,  if  at  all.  The  trouble  becomes  established  in  the  soil 
when  garbage  is  dumped  on  it  or  the  refuse  from  the  diseased 
crop  is  left  in  the  fields.  For  this  reason  infected  land  is  not 
adapted  for  raising  cabbage  or  the  similar  cruciferous  plants, 
cauliflower,  turnip,  etc.  The  disease  even  spreads  to  cruciferous 
weeds  in  the  fields,  as  shepherd  purse,  and  pepper  grass. 
Rotation  with  different  crops  should  be  followed.  The  young 
plants  should  never  be  grown  in  infected  soil.  If  an-  infected 
field  is  ever  used,  a  fall  coating  with  lime  sown  broadcast  at 
the  rate  of  eighty  bushels  per  acre,  is  said  to  be  helpful  in  keep- 
ing the  trouble  in  check.     [Bull.  142,  p.  5.] 

Leaf  Molds^  Alternaria  Brassicce  (Berk.)  Sacc,  A.  BrassiccB 
var.  macrospora  Sacc.  These  cause  subcircular,  blackish  spots 
of  varying  size  on  the  leaves.  The  variety  seems  to  be  the 
more  common  and  has  very  large  spores  as  seen  under  the 
microscope.  The  same  fungus  occurs  on  mustard  and  radish. 
Occasionally  the  trouble  becomes  rather  prominent. 

Soft  Rot^  Bacterial.  Often  the  leaves  of  the  heads  are  more 
or  less  destroyed  by  a  wet  brown  rot,  which  may  become  serious. 

CAENATION,  Dianthus  Caryophyllus. 

Fairy  Ring,  Heterosporium  eckinulatum  (Berk.)  Cke.  This 
forms  on  the  leaves  greyish  spots,  about  a  quarter  of  an  inch 
in  diameter,  having  a  distinct  purplish  border.  The  fruiting 
stage  shown  under  a  lens  is  an  olive  black,  upright  growth  of 
threads.  When  occurring  on  the  calyx,  it  often  causes  this  to 
crack  open,  which  is  very  objectionable  to  the  growers.  Usually 
the  trouble  occurs  seriously  only  in  neglected  houses.  [Bull. 
142,  p.  5-1 

Grey  Mold,  Botrytis  vulgaris.  vSometimes  occurs  on  the 
blossoms.     See  Lettuce. 

Leaf  Spot,  Septoria  Dianthi  Desm.     This  often  occurs  with 

the  preceding  and  the  two  look  very  similar.     The  leaf  spot  can 

usually  be  distinguished  by  the  small  black  dots,  or  fruiting 

receptacles,  that  are  embedded  in  the  center  of  the  spots.     Only 

21 


312        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

good  plants  should  be  selected  for  cuttings  and  all  dead  leaves 
removed  as  they  appear.  Care  is  needed  in  watering.  It  is 
easier  to  keep  out  these  troubles  by  giving  the  plants  the  very 
best  treatment  than  it  is  to  control  them  after  they  are  thoroughly 
started. 

Rust,  Uromyces  caryophyllinus  (Schrank.)  Schrt.  Plate 
XV,  b.  Rust  is  the  most  troublesome  of  the  fungous  pests  of 
carnation.  It  breaks  out  in  reddish  brown  dusty  pustules 
on  the  leaves  and  stems.  Both  uredo-  and  teleuto-spores  occur, 
but  the  former  are  more  common.  There  is  considerable  differ- 
ence in  the  susceptibility  to  rust  with  the  various  varieties. 
Eldorado,  Daybreak,  Jubilee,  and  others  are  said  to  rust  badly, 
while  Prosperity,  Portia,  etc.,  are  more  exempt.  The  conditions 
of  different  greenhouses  and  the  care  given  by  the  growers  also 
make  differences  in  the  amount  of  rust.  Plants  crowded  too 
closely  or  watered  too  freely  on  the  foliage  and  at  improper 
times  rust  the  worst.  Many  growers  remove  the  rusted  leaves, 
if  not  too  numerous.  No  doubt  very  careful  attention  to  this 
treatment  when  the  plants  are  first  started  and  little  rust  is 
found,  would  always  repay.  Spraying  experiments  have  been 
carried  on  to  some  extent.  Bordeaux  mixture  is  objectionable 
to  the  grower  on  account  of  the  sediment.  Potassium  sulphide 
to  be  of  value  should  be  applied  in  season,  and  repeatedly. 
[Bull.  142,  p.  5.] 

Stem  Rot_,  Rkisoctonia  sp.  This  sterile  fungus  was  found  in 
connection  with  the  rot  in  one  greenhouse.  As  the  fungus  lives 
in  the  soil,  it  is  desirable  to  keep  it  from  becoming  established, 
since  it  will  attack  other  plants  as  well. 

Wilt,  Fusarium  sp.  In  the  Report  for  1897,  pp.  175-81,  Dr. 
Sturgis  reports  this  troublesome  to  carnations  grown  in  the 
Experiment  Station  greenhouse.  Perhaps  both  this  and  the 
preceding  fungus  are  responsible  for  the  common  stem  rot 
trouble  of  growers.  The  soil,  if  necessary,  can  be  sterilized 
with  steam  to  rid  it  of  these  fungi. 

CARROT,  Daiicus  Carota. 

Blight,  Bacterial.  While  visiting  a  seed  farm  in  the  vicinity 
of  Milford  in  1902,  there  was  observed  a  rather  serious  trouble 
of  this  host  due  to  bacteria.  The  infected  plants  showed  a  wet 
rot,   confined  chiefly  to  the  outer  layers   of  the  stem.     These 


NOTES    ON    PARASITIC    FUNGI.  313 

had  a  greenish  black  color,  were  watery  and  easily  mashed  out 
of  place  with  handling.  To  a  less  extent  the  leaves  showed 
blackened  spots  and  the  inflorescence  was  somewhat  infected. 
An  examination  of  these  injured  parts  showed  plenty  of  bacteria, 
which  were,  no  doubt,  the  cause  of  the  trouble,  though  no  experi- 
mental or  cultural  work  was  undertaken  with  them.  So  far 
the  writer  has  seen  no  description  by  others  of  this  trouble  on 
the  carrot. 

CATALPA,  Catalpa  sps. 

Powdery  Mildew,  Microsphcera  elevata  Burr.  In  nurseries 
especially,  but  occasionally  on  the  shade  trees  of  lawns,  this 
fungus  is  found  coating  the  leaves  on  their  upper  surface  with 
a  more  or  less  conspicuous  cobweb-like  growth.  Imbedded  in 
the  dirty  white  mycelium  occur  the  small  black  receptacles  con- 
taining the  winter  or  asco-spores.  In  the  nurseries  the  trouble 
ought  to  be  easily  controlled  by  spraying  with  potassium 
sulphide. 

CEDAR,  Jimiperus  Virginiana. 

Cedar  Apples,  Gynmosporangium  macropus  Lk.,  G.  gloho- 
sitm  Farl.  Colortype  2.  The  teleutal  stage  of  apple  rusts  occurs 
on  this  host.  The  "cedar  apples"-  are  reddish  gall-like  bodies 
that  in  the  moist  weather  of  spring  send  out  elongated  jelly- 
like horns  all  over  their  surface.  These  contain  spores  that 
germinate  in  position  and  produce  smaller  thin-walled  spores, 
that,  on  the  drying  of  the  horns,  are  carried  by  the  wind  to  the 
apple  leaves,  where  their  infection  produces  the  cluster  cup 
stage.  The  two  species  on  the  cedar  are .  distinguished  by  the 
longer,  more  tapering  horns  of  G.  macropus,  which  is  the  more 
common  species.     See  Apple. 

CELERY,  Apmm  graz'eolens. 

Leaf  Blight,  Cercospora  Apii  Fr.  The  so-called  "rust"  of 
growers  shows  as  reddish  brown  irregular  spots  on  the  leaves. 
If  badly  infected,  these  turn  yellowish  and  have  a  sickly  appear- 
ance. The  fungus  can  usually  be  seen  by  a  hand  lens  as  a 
not  very  evident  upright  surface  growth.  This  is  one  of  the 
most  serious  troubles  of  the  celery  grower.  At  bleaching  time 
rusty  spots  of  this  or  the  next  fungus  may  appear  on  the  stalks. 


314        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I903. 

Where  the  trouble  is  Hkely  to  prove  serious,  spraying  should 
begin  soon  after  transplanting.  Bordeaux  is  used  for  the  first 
and  usually  Amm.  Sol.  Cop.  Carbonate  for  the  later  sprayings. 
Applications  should  be  made  about  every  two  weeks  up  to  the 
time  of  banking.  Sturgis  found  that  dusting  sulphur  over  the 
plants  was  also  an  effective  treatment.  [Reps.  1892,  p.  44; 
1893,  pp.  81,  103  ;  1897.  P-  167;  Bull.  142,  p.  5.] 

Leaf  Spot,  Septoria  Petroselini  var.  Apii  Br.  &  Cav.  This 
is  a  trouble  very  similar  to  the  preceding  and  the  preventive 
treatment  is  the  sam.e.  The  two  may  occur  together;  but  the 
leaf  spot  is  usually  distinguished  by  the  small  black  dots,  or 
fruiting  receptacles,  in  the  rusty  spots. 

CHAEB,  Beta  vulgaris  var. 
Leaf  Blight,  Cercospora  heticola  Sacc.     See  Beet. 

CHEERY,  Prunus  sps. 

Black  Knot,  Ploivrightia  morbosa  (Schw.)  Sacc.  Occurs 
injuriously  on  cultivated  species  and  also  on  the  wild  species, 
Prunus  serotina  and  P.  V.irginiana.     See  Plum. 

Brown  Rot,  Sclerotinia  fructigena   (Pers.)    Schrt.     Occurs  ' 
on  both  Prumts  Cerasus  and  P.  Avium.  ~  See  Peach. 

Leaf  Curl,  Exoascus  Cerasi  (Fckl.)  Sad.  The  leaves 
become  badly  discolored  and  somewhat  deformed  when  attacked 
by  this  fungus.  Those  worst  infected  usually  drop  off.  The 
trouble,  apparently,  is  not  common,  but  was  collected  a  few  times 
in  1900  by  Sturgis. 

Leaf  Spot,  Cylindrosporium  Padi  Karst.  Colortype  11. 
The  crowded,  small,  purplish  spots  produced  on  the  upper  sur- 
face of  the  leaves  by  this  fungus  are  shown  very  well  by  the 
colortype  frontispiece.  On  the  under  surface  the  spores  fre- 
quently show  as  small,  pinkish,  agglutinated  masses.  Badly 
infected  leaves  turn  yellowish  and  drop  off.  The  trouble  is  one 
of  the  most  common  and  serious  occurring  on  the  cherry;  it 
also  occurs  on  the  wild  black  cherry,  P.  serotina,  and  occasionally 
on  cultivated  plums.  Spraying  with  Bordeaux  mixture,  start- 
ing early  in  May,  has  successfully  prevented  the  disease  else- 
where.    [Rep.  1890,  p.  102;  1895,  p.  188;  Bull.  142,  p.  6.] 

Powdery  Mildew,  Podosphcera  oxyacanthce  (DC)  DeBy. 
Plate  XV,   c.     This  is  most  injurious  to  young  trees.     The 


NOTES   ON    PARASITIC    FUNGI.  31$ 

under  surface  of  the  leaves,  and  to  some  extent  the  upper, 
becomes  covered  with  the  white  myceHum  of  the  fungus.  In 
the  fall,  the  winter  spore  stage  is  conspicuous,  through  the 
numerous  small  black  perithecia  (Plate  XV,  c)  scattered  among 
the  fungous  threads.  The  trouble  can  readily  be  controlled  in 
the  nurseries  where  it  is  injurious,  by  spraying  either  with 
Bordeaux  mixture  or  potassium  sulphide,  if  taken  in  time. 
[Bull.  142,  p.  6.] 

CHESTNUT,  Castanea  sativa. 

Anthracnose^  Marsonia  ochroleuca  (B.  &  C.)'  Humph. 
Colortype  5.  This  forms  conspicuous  spots  with  brownish  cen- 
ters and  purplish  borders,  on  the  leaves.  It  is  most  injurious 
to  young  nursery  trees,  but  probably  could  be  prevented  by 
proper  spraying. 

CHRYSANTHEMUM,  Chrysanthemum  Sinense. 

Anthracnose,  Cylindrosporium  Chrysanthemi  Ell.  &  Dearn. 
Greenhouse  chrysanthemums  sometimes  suffer  from  this  trouble. 
It  produces  large,  brownish  or  blackish  spots  or  blotches,  some- 
times covering  the  entire  leaf. 

Powdery  Mildew,  Oidium  Chrysanthemi  Rabh.  This  is  a 
very  common  trouble  in  greenhouses,  the  leaves  becoming  cov- 
ered with  a  mealy  white  growth.  Apparently  it  is  only  the 
conidial  stage  of  one  of  the  Erysipheas,  but  the  winter  stage  is 
never  produced.  Ada  Prass,  Colonel  Appleton,  Omega,  Merula 
and  Julinda  apparently  mildew  worse  than  Major  Bonnaffon, 
Glory  of  Pacific,  George  W.  Childs,  or  Ivory.  The  treatment 
for  this  should  be  the  same  as  for  mildew  of  rose,  q.  v. 

Rust,  Puccinia  Chrysanthemi  Roze.  Plate  XV,  d.  Only  the 
uredo-stage  of  this  rust  seems  to  occur  in  this  country  on  the 
chrysanthemum.  This  is  a  recent  trouble,  though  one  of  the 
worst  of  this  host.  The  dusty  outbreaks  of  the  reddish  brown 
spores  are  about  the  size  of  a  pin-head.  These  occur  more  or 
less  abundantly  on  the  under  surface  of  the  leaves.  Attention 
should  be  given  to  the  removal  of  infected  leaves  as  soon  as 
seen.  Queen,  Black  Hawk,  Ada  Prass,  Timothy  Eaton,  seem 
to  rust  worse  than  Miss  Pullman,  Major  Bonnaffon,  V.  H. 
Hallock. 


3l6        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O3. 

CLEMATIS,  Clematis  Virginiana. 
Leaf  Spot,  Cylindrosporium  Clematidis  Ell.  &  Ev. 

CLOVER,  RED,  Trifolium  pratense. 

Black  Dot,  Phyllachora  Trifolii  (Pers.)  Fckl.  Colortype  6. 
The  under  surfaces  of  the  leaves  are  usually  rather  thickly  cov- 
ered by  the  small  black  pustules  of  this  fungus.  It  also  occurs 
on  white  clover  (T.  repens)  and  crimson  clover  (T.  incarnatum) . 
It  is  not  uncommon  in  clover  fields. 

Black  Mold,  Macrosporium  sarcinceforme  Cav.  This  is  also 
troublesofne  in  some  clover  fields.  It  produces  on  the  leaves 
reddish  circular  spots  that  often  show  faint  concentric  rings  of 
development.  The  fruiting  stage  is  very  inconspicuous  on  these 
spots. 

Leaf  Spot,  Pseud opeziza  Trifolii  (Bernh.)  Fckl.  So  far  this 
fungus  has  not  been  found  very  common  on  the  leaves,  where  it 
produces  irregular  reddish  brown  spots,  in  the  center  of  which 
may  sometimes  be  seen  the  small  fruiting  disc. 

Rust,  Uromyces  Trifolii  (A.  &  S.)  Wint.  Plate  XVI,  a. 
the  secidial  or  cluster  cup  stage  was  collected  by  Thaxter  in 
June  on  white  clover.  Apparently  this  is  not  so  common  as  the 
uredo-  and  teleuto-stages,  which  are  found  in  July  and  August 
very  commonly  on  red  and  white  clover.  They  appear  chiefly 
on  the  under  surface  of  the  leaves  as  reddish,  dusty  pustules. 
Perhaps  this  is  the  most  abundant  and  injurious  of  these  clover 
fungi ;  it  is  not  uncommon  to  find  two  or  more  of  them  on  the 
same  leaves.     [Reps.  1889,  p.  174;   1890,  p.  98.] 

COLUMBINE,  Aquilegia  sp. 

Leaf  Spot,  Ascochyta  sp.  The  large  purplish  blotches  or 
diseased  areas  often  seen  on  the  leaves  of  cultivated  columbines 
seem  to  be  caused  by  a  species  of  Ascochyta,  one  of  the  imperfect 
fungi. 

Powdery  Mildew,  Erysiphe  Polygoni  DC.  Occasionally 
this  is  found  forming  a  whitish  mycelial  growth,  with  plenty 
of  the  perithecia  showing  as  small  black  specks,  scattered  over 
the  surface  of  the  leaves. 


NOTES    ON    PARASITIC    FUNGI.  31/ 

CORN,  Zea  Mays. 

Blight,  Bacillus  Zea:  Burr.  This  usually  occurs  on  the 
inner  surface  of  the  leaf  sheaths,  where  it  produces  very  evident 
dark  purplish  discoloration  showing  slightly  through  the  sheath. 
Apparentl)^  it  is  not  a  serious  trouble  in  Connecticut. 

Leaf  Blight,  Helminthospormm  turcicum  Pass.  {H.  incon- 
spicuum  Ell.  &  Ev.).  Colortype  13.  Last  year  this  proved  a 
very  serious  trouble  to  corn,  many  fields  looking  in  August  or 
September  as  if  struck  by  an  early  frost.  The  very  unfavorable 
season  for  maturing  the  corn  was  largely  responsible  for  this 
unusual  attack.  Elongated  areas  or  even  entire  leaves  were 
killed,  turning  a  brownish  color  and  showing  the  fungus  as  a 
very  inconspicuous  surface  growth.  Conspicuous  growths  of 
other  saprophytic  molds,  however,  often  appeared  on  these  dead 
areas.  Sometimes  the  dead  spots  were  small,  but  usually, 
because  of  the  venation,  they  developed  into  elongated  areas. 
Not  all  fields  were  equally  affected  and  it  was  difficult  to  always 
explain  this.  Possibly  the  maturity  of  the  plants,  or  the  charac- 
ter of  the  seed  from  which  they  came,  was  a  partial  explanation. 
Thaxter  noted  this  as  a  serious  trouble  in  Connecticut  in  1889. 
[Rep.  1889,  p.  171.] 

Rust,  Puccinia  Sorghi  Schw.  Apparently  this  possesses  no 
cluster  cup  stage.  Both  the  uredo-  and  teleuto-spores  develop 
as  reddish,  dusty  outbreaks  on  either  surface  of  the  leaves, 
and  can  usually  be  distinguished  by  their  color.  While  not  an 
uncommon  fvmgus  in  the  corn  fields,  it  does  not  often  prove  to 
be  ver}^  serious. 

Smut,  Ustilago  Zece  (Beckm.)  Ung.  Plate '  XVI,  b.  The 
conspicuous  dusty  smut  balls  of  this  fungus  are  familiar  to  every 
one.  They  break  out  on  any  part  of  the  host  and  vary  greatly 
in  size  and  shape  according  to  their  situation.  These  smutty 
masses  are  composed  entirely  of  spores.  The  trouble  is  most 
serious  in  sweet  corn.  Fresh  manure  applied  to  the  land  is 
likely  to  increase  the  amount  of  smut  in  corn,  since  the  spores 
germinate  in  this  and  give  rise,  yeast-fashion,  to  numerous 
secondary  germs  that  have  the  power  of  infecting  the  corn. 
This  is  practically  the  only  cereal  smut  that  can  not  be  pre- 
vented by  seed  treatment,  as  infection  takes  place  through  any 
very  young  tissue.  Some  gather  the  smut  balls  to  keep  the 
trouble  from  spreading,  but  it  is  questionable  just  how  much 


3l8        CONNECTICUT   EXPERIMENT   STATION    REPORT^    I903. 

good  this  does.     This  smut  is  not  poisonous  to  stock,  as  is  sup- 
posed by  some.     [Rep.  1889,  p.  171 ;   Bull.  142,  p.  6.] 


COSMOS,  Cosmos  bipinnatus. 

Leaf  Spot,  Septoria  sp.  Occasionally  brown  circular  spots 
are  produced  more  or  less  abundantly  in  the  leaves  by  a  Septoria 
fungus,  whose  fruiting  bodies  show  as  the  usual  little  black 
dots  in  the  tissues. 

COSMOS,  Cosmus  bipinnatus. 

Stem  Spot,  Phlyctcea  sp.  Halsted,  of  New  Jersey,  gives  this 
as  the  cause  of  the  large  purplish  blotches  that  appear  on  the 
stems,  especially  at  the  lower  nodes.  It  may  eventually  produce 
a  more  or  less  serious  rot  of  the  stems. 

CRAB  APPLE  (Beditel's),  Pirus  lonensis  var. 

Rust,  Gymnosporangium  macropus  Lk.  This  occurs  in  its 
aecidial  stage,  I,  on  the  branches,  as  well  as  on  the  leaves,  but 
it  does  not  seem  to  carry  over  the  winter  in  the  branches,  as 
an  examination  last  spring  of  those  infected  the  year  before 
failed  to  show  any  signs  of  a  new  development  of  the  fungus. 
See  Apple. 

CEOWEOOT,  Ranunculus  sp. 

Powdery  Mildew,  Erysiphe  Polygoni  DC.  Only  the  coni- 
dial  stage  was  found  forming  a  mealy  whitish  growth  over  the 
leaves. 

CUCUMBER,  Cucumis  sativus. 

Anthracnose,  CoUetotrichtim  Lagenarium  (Pass.)  Ell.  & 
Hals.     See  Watermelon. 

Downy  Mildew^,  Plasmopara  Cubensis  (B.  &  C.)  Humph. 
This  fungus  does  not  produce  so  conspicuous  spots  on  the  leaves 
of  this  host  as  it  does  on  the  musk  melon;  neither  is  the  injury 
so  severe.  The  fruiting  stage,  however,  shows  more  con- 
spicuously and  with  a  lens  the  scattered  growth  of  upright 
fertile  threads  bearing  the  large  dark  purple  spores  is  easily 
made  out.  Spraying  gives  beneficial  results  with  this  host. 
Bordeaux  should  be  used  as  soon  as  the  vines  begin  to  run 


NOTES    ON    PARASITIC    FUNGI.  319 

and  the  treatments  should  be  given  often  enough  to  keep  the 
foHage  well  covered  with  the  sediment.  The  cucumbers  may 
be  picked  before  each  of  the  later  sprayings,  otherwise  no 
attention  need  be  given  to  keep  the  spray  off  the  fruit.  See 
Musk  Melon.     [Rep.  1890,  p.  97.] 

Powdery  Mildew^  Erysiphe  dehor acearum  DC.  Conidial 
stage  only  occurs  ;  on  the  leaves. 

ScAB^  Cladosporium  cucumerinum  Ell.  &  Arth.  On  leaves 
and  fruit.     See  Musk  Melon. 

WiLT^  Bacillus  tracheiphilus  Sm.     See  Squash. 

CUREANT,  Ribes  ruhrum. 

Anthracnose,  Glozosporium  Ribis  (Lib.)  Mont  &  Desm. 
This  is  the  most  serious  trouble  of  the  currant.  It  causes 
numerous  purplish  or  reddish  brown  spots,  about  the  size  of  a  pin 
head,  on  the  upper  surface  of  the  leaves.  Where  abundant,  the 
intervening  tissue  is  also  killed  and  the  leaf  sheds  prematurely. 
On  the  under  surface  of  these  spots  the  spores  show  in  small 
pinkish  globules.  The  trouble  is  often  so  serious  that  the  bushes 
are  completely  defoliated  by  August,  thus  cutting  short  their 
season  of  usefulness.  Spraying  experiments,  elsewhere,  have 
controlled  this  disease.  The  first  treatment  is  given  before  the 
leaves  appear;  the  second  as  they  are  unfolding;  others  follow 
at  intervals  of  about  two  weeks  until  the  fruit  begins  to  turn. 
[Bull.  142,  p.  7.] 

Leaf  Spot,  f  Septoria  Ribis  Desm.  This  forms  larger  and 
fewer  spots  than  the  last  and  the  spores  ooze  out  on  the  upper 
surface.  Apparently  it  is  not  common.  The  spots  and  spores 
are  not  quite  like  those  this  fungus  produces  on  the  goose- 
berry, q.  V. 

Red  Knot,  Nectria  Ribis  (Tode)  Rab.  Plate  XVI,  c.  This 
was  found  on  currants  badly  infested  with  the  San  Jose  scale, 
which  was  chiefly  responsible  for  the  poor  condition  of  the 
bushes.  It  is  a  question  whether  the  fungus  does  not  occur 
more  commonly  as  a  saprophyte  than  a  parasite.  It  can  be 
told  by  the  bright  red  fruiting  bodies  that  break  out  in  roundish 
clusters  on  the  stems.  These  are  often  accompanied  by  a  coni- 
dial stage  {Tuber cularia  vulgaris),  which  forms  small  roundish 
pink  cushions  producing  the  summer  spores.  It  will  do  no  harm 
t6  cut  out  all  diseased  branches. 


320        CONNECTICUT    EXPERIMENT   STATION    REPORT,    I903. 

DAHLIA,  Dahlia  variahilis. 

Powdery  Mildew,  Erysiphe  cichoracearum  DC.  Conidial 
stage  only  formed. 

DANDELION,  Taraxacum  officinale. 

Powdery  Mildew,  Sphaerotheca  Castagnei  Lev.  Found 
sometimes  on  plants  raised  for  greens. 

DEWBERRY,  Rubus  Canadensis. 

Leaf  Spot,  Septoria  Riihi  Westd.     See  Blackberry. 
Orange    Rust,    Gymnoconia   inter stitialis    (Schl.)    Lagerh. 
See  Blackberry. 

DOGWOOD,  Cornus  sps. 

Leaf  Spot,  Septoria  cornicola  Desm.  This  fungus  produces 
numerous  brownish  or  purplish  circular  spots,  usually  less  than 
one-quarter  of  an  inch  in  diameter,  on  the  leaves.  It  was  found 
doing  considerable  injury  to  both  Cornus  sanguinea  and  C. 
paniculata  in  nursery  rows. 

EGG  PLANT,  Solanum  Melongena. 

Fruit  Mold,  Botrytis  sp.  This  is  often  responsible  for  the 
rotting  of  the  fruit.  Its  spore  stage  shows  as  a  dense  greyish 
moldy  growth  covering  the  rotten  area. 

Fruit  Rot  and  Leaf  Spot,  Phyllosticta  hortorum  Speg. 
This  was  a  serious  trouble  last  year  of  t.gg  plants,  especially 
on  the  fruit.  It  causes  round  brownish  spots  on  the  leaves 
and  the  fruit  gradually  rots  a  reddish  brown  color,  the  spore 
pustules  showing  as  black  dots.  The  spores  produced  in  the 
leaves  are  often  septate  and  possibly  larger  than  those  on  the 
fruit.  A  Phlyctcena  spore  stage  also  often  occurs  in  the  same 
pustules  on  the  fruit  with  the  Phyllosticta.  This  makes  the 
systematic  position  of  the  fungus  uncertain,  though  Halsted 
determines  it  as  given  above.  The  rotten  fruit  should  be  picked 
and  destroyed. 

Leaf  Mold,  Alternaria  Solani  (E.  &  M.)  J.  &  G.  This 
forms  spots  on  the  leaves  very  similar  to  the  above  fungus.  See 
Potato. 


NOTES    ON    PARASITIC    FUNGI.  321 

Wilt.  Last  year  the  egg  plants  were  often  attacked  by  a 
fungus  that  caused  wilting,  yellowing  and  eventually  the  death 
of  the  leaves,  especially  the  lower  ones.  This  spemed  to  be  the 
result  of  a  Fusarium  that  invaded  the  fibro-vascular  bundles  of 
the  stern  and,  by  clogging  the  vessels,  cut  off  the  water  supply 
of  these  leaves. 

ELM,  Ulmus  Americana. 

-Leaf  Spot^  Gnomonia  ulmea  (Schw.)  Thm.  Elm  leaves  are 
very  commonly  attacked  by  this  fungus,  its  fruiting  stage  show- 
ing on  the  upper  surface  as  small  black  pimples,  often  somewhat 
clustered  in  circles.  The  spores  mature  in  the  old  dead  leaves 
the  following  spring. 

White  Fungus,  Sporotrichiim  glohuliferum  Speg.  Plate 
XVI,  d.  This  is  the  fungus  that  was  used  some  years 
ago  by  the  Kansas  and  Illinois  Experiment  Stations  in  experi- 
ments to  infect  chinch  bugs  generally  in  the  fields.  In  the 
summer  and  fall  of  1902,  it  was  found  in  Connecticut  on  the 
elm-leaf  beetles,  and  as  the  next  year  the  beetles  were  greatly 
reduced  in  numbers  it  no  doubt  had  considerable  influence  in 
checking  their  ravages.  The  remains  of  the  larvae  were  fre- 
quently found  under  the  loose  bark  of  the  trees,  embedded  in  a 
luxuriant  white  growth  of  the  fungus  (see  Plate) .  Under  a  hand 
lens  this  shows  the  spores  crowded  into  the  numerous  minute 
spore  balls  so  characteristic  of  the  fungus. 

ENDIVE,  Cichorium  Endivia. 

Leaf  Spot.  A  serious  leaf  spot  trouble,  apparently  produced 
by  a  fungus  but  not  in  a  fruiting  condition,  was  observed  in 
1902  in  the  vicinit}^  of  New  Haven.  The  leaves  were  so  abun- 
dantly covered  with  the  circular  brown  spots  as  to  render  them 
useless  for  the  market. 

Rust,  Puccinia  Endivice  Pass.  Apparently  this  rust  has  not 
been  reported  before  in  this  country,  though  it  is  a  common 
parasite  of  endive  in  Italy.  It  was  probably  introduced  in  New 
Haven  from  that  country,  for  the  only  place  it  was  found  was 
in  a  large  endive  field  owned  by  an  Italian  market  gardener. 
As  endive  should  have  perfect  leaves  for  bleaching,  the  abundant 
dusty  pustules  produced  by  the  rust  spoiled  many  plants  or  at 
least  rendered  them  second  class.  Only  the  uredo-spores  were 
found,  even  late  in  the  fall. 


322        CONNECTICUT    EXPERIMENT   STATION    REPORT,    I903. 

GERANIUM,  Pelargonium  sp. 

Grey  Mold,  Botrytis  vulgaris  Fr.  This  common  mold  occurs 
in  leaky  or  too  moist  greenhouses.  Water  dropping  on  the 
plants  from  the  roof  often  gives  the  fungus  its  chance  for  infec- 
tion. Brown  dead  spots  are  produced  on  the  leaves  and  under 
moist  conditions  these  develop  the  grey,  moldy  growth  of  the 
fruiting  stage. 

Leaf  Spot,  Ascochyta  sp.  Produces  large  circular  or  irregu- 
lar spots  on  the  leaves ;  not  very  common. 

Stem  and  Leaf  Rot,  Bacterial.  Complaint  is  sometimes 
made  of  geraniums  rotting  off  at  their  base  or  the  leaves  decay- 
ing or  spotting.  The  trouble  seems  to  be  caused  by  bacteria 
and  no  doubt  is  often  induced  by  too  moist  conditions.  Affected 
parts  or  badly  diseased  plants  should  be  destroyed. 

GOLDEN  GLOW,  Rudheckia  laciniata. 

Powdery  Mildew,  Erysiphe  cichoracearum  DC.  Common, 
but  not  very  injurious,  and  occurring  only  in  the  conidial  stage. 

Stem  Rot.  The  writer's  attention  has  been  called  to  a  stem 
rot  trouble  of  golden  glow  that  has  appeared  year  after  year 
in  the  same  bunch.  Each  year  the  rot  attacks  some  of  the  stems 
at  their  base,  finally  killing  them  by  rotting  the  tissues  and 
choking  up  the  water  ducts.  The  trouble  is  carried  over  in 
the  soil  by  small  black  sclerotia,  or  compacted  tubers  of  fungous 
cells,  that  are  formed  on  the  rotting  stems.  The  trouble  is 
probably  caused  by  a  Botrytis  fungus. 

GOOSEBERRY,  Rihes  sps. 

Anthracnose,  Glososporium  Ribis  (Lib.)  Mont.  &  Desm. 
Occurs  occasionally  on  this  host.     See  Currant. 

Leaf  Spot,  Septoria  Ribis  Desm.  Brownish  or  purplish 
spots,  often  having  a  whitish  center,  are  formed  on  the  leaves. 
The  fruiting  bodies,  as  minute  black  dots,  may  sometimes  be  seen 
in  these.     Apparently  this  is  not  a  common  trouble. 

Powdery  Mildew,  Sphcerotheca  mors-uvce  (Schw.)  B.  &  C. 
While  this  has  never  been  collected  by  the  Station  botanists,  it 
has  occurred  in  the  state,  as  shown  by  reference  to  it  in  one  of 
the  old  Reports  of  the  Agricultural  Society,  where  it  was  named 
as  a  serious  trouble  varying  in  different  seasons.     It  forms  a 


NOTES    ON    PARASITIC    FUNGI.  323 

dirty  white  felt  of  mycelium  on  the  young  branches  and  leaves 
and  often  on  the  fruit.  Imbedded  in  this  are  the  small  reddish 
black  perithecia,  containing  the  asco-  or  winter  spores.  Spray- 
ing with  potassium  sulphide,  beginning  as  soon  as  the  buds 
burst  and  repeating  every  two  weeks  until  the  end  of  June,  is 
said  to  hold  this  trouble  in  check. 


GrRAPE,  FiVw  sps. 

Anthracnose^  Sphaceloma  ampelinum  DeBy.  The  bird's 
eye  rot  occurs  on  the  leaves,  stems  and  fruit.  On  the  latter  it 
forms  circular  rotten  spots  with  distinct,  bright  colored  borders, 
hence  the  common  name.  This  generally  yields  to  treatment  by 
spraying  more  readily  than  the  next  trouble.  Diseased  wood 
should  be  removed.  [Reps.  1889,  p.  174;  1890,  p.  102;  1893, 
p.  98.] 

Black  Rot,  Guignardia  Bidwellii  (Ell.)  Viala  &  Rav.  Plate 
XVII,  a.  This  is  the  most  common  and  injurious  trouble  of 
the  grape.  On  the  leaves  it  produces  conspicuous,  circular,  red- 
dish brown  spots.  In  the  small  black  dots  imbedded  in  these 
are  produced  one  of  the  summer  spore  stages  (  Phyllosticta  Lab- 
rusccB  Thm.)  of  the  fungus.  This  stage  also  occurs  on  the 
leaves  of  the  Virginia  creeper  and  the  Boston  ivy,  which  are 
related  plants.  The  grapes,  on  rotting,  first  have  a  brown  color, 
but  eventually  dry  up  into  wrinkled  black  mummies  that  adhere 
for  some  time  to  the  vine.  In  these,  a  summer  spore  stage, 
similar  to  that  on  the  leaves,  is  first  produced,  but  other  stages 
are  also  formed,  the  asco-spore  form  appearing  the  next  spring. 
Black  rot  is  a  very  difficult  trouble  to  control,  especially  in  wet 
seasons,  but  persistent  spraying  year  after  year  reduces  the 
trouble  to  a  minimum.  Spraying  should  begin  before  the  blos- 
soming period,  about  the  last  of  May;  the  second  applica- 
tion follows  after  the  plants  blossom,  and  others  at  intervals  of 
ten  to  fourteen  days.  Bordeaux  is  used  until  the  middle  of 
July,  and  then  Amm.  Sol.  Cop.  Carbonate  or  Soda  Bordeaux 
until  the  middle  of  August.  The  treatment  should  be  thorough 
for  a  couple  of  years  until  the  disease  is  under  control,  when 
the  number  of  sprayings  can  be  reduced  from  six  or  seven  to 
three.  [Reps.  1889,  p.  174;  1890,  p.  100;  1893,  p.  96;  Bull. 
142,  p.  8.] 


324        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

Downy  Mildew,  Plasmopara  viticola  (B.  &  C.)  Berl.  &  De 
Toni.  Plate  XVII,  b.  This  fungus  occurs  on  grapes  grown 
under  glass,  in  the  vineyards,  and  even  more  commonly  on  wild 
species.  The  thick,  white  felt  that  is  produced  on  the  under 
surface  of  the  leaves,  occasionally  on  the  stems  and  fruit,  bears 
the  thin-walled  summer  spores ;  the  thick-walled  winter  spores 
are  rarely  formed  within  the  tissues.  The  treatment  given  for 
black  rot  should  prevent  this  trouble  also.  When  the  vines  are 
treated  for  this  alone,  perhaps  the  sprayings  need  not  be  so 
numerous.  For  grapes  grown  under  glass,  Sturgis  found  the 
fumes  of  sulphur  safer  tO'  use.  [Rep.  1893,  pp.  yy,  97;  Bull. 
142,  p.  8.-] 

Grey  Mold,  Botrytis  sp.  Ripe  fruit  of  greenhouse  grapes 
frequently  rots  by  reason  of  a  common  Botrytis  mold.  .  Atten- 
tion should  be  paid  to  the  moisture  conditions  in  these  houses. 
Spraying  tihe  bunches  with  potassium  sulphide  or  heating  sul- 
phur, probably  would  prove  helpful.  The  rotting  grapes  should 
be  removed  as  soon  as  they  appear. 

Powdery  Mildew,  Uncinula  necator  (Schw.)  Burr.  This 
mildew  forms  a  cobweb-like  growth  on  the  upper  surface  of  the 
leaves  or  occasionally  destroys  the  fruit.  In  the  fall  the  peri- 
thecia  are  easily  seen  as  very  minute  reddish  or  black  balls 
scattered  over  the  surface  of  the  infected  leaves.  The  treatment 
for  black  rot  should  also  prevent  this.  Where  this  alone  is 
troublesome,  the  later  sprayings  may  be  made  with  potassium 
sulphide,  if  desired.  Probably  a  very  late  spraying  in  the  fall 
would  prove  useful  in  checking  the  trouble  the  next  year.  The 
Virginia  creeper  is  also  a  host  for  the  fungus.  [Rep.  1895, 
p.  185 ;  Bull.  142,  p.  8.] 

Winter  Injury.  A  very  curious  trouble  was  seen  the  past 
summer  on  grapes  grown  under  glass  in  New  Haven.  Appar- 
ently it  was  a  result  of  the  sudden  freeze  of  December  9,  1902, 
since  the  greenhouse,  contrary  to  the  usual  custom,  was  not 
heated  that  winter  and  the  injury  was  greatest  on  the  west 
or  coldest  side  of  the  house.  The  trouble  first  showed  during 
the  summer  in  morbid,  gall-like  growths  of  plant  tissue,  that 
were  formed  usually  at  or  toward  the  base  of  the  vines.  These 
excrescences  were  more  irregular  and  not  so'  dark  colored  as 
black  rot.  By  early  winter  this  morbid  tissue  was  dead  and 
somewhat  pulverized  by  insect  larvae.     A  similar  trouble  has 


NOTES    ON    PARASITIC    FUNGI.  325 

been  figured  in  one  of  the  New  York  Experiment  Station's 
bulletins  on  grapes  grown  outdoors  ;  and  has  also  been  described 
in  Europe.  It  has  usually  been  ascribed  to  cold  weather.  As 
the  wood  on  some  of  the  vines  described  here  also  showed  winter 
cracks,  this  is  probably  the  explanation  of  the  trouble. 

GrROTJND    CHEEEY,  Phy sails  puhescens. 

White  Smut,  Entyloma  Physalidis  (Kalchb.  &  Cke.)  Wint. 
The  spores  of  the  white  smuts  are  permanently  embedded  in 
the  tissues,  and  of  light  color,  so  they  do  not  have  the 
black,  dusty  appearance  of  the  ordinary  smuts.  This  smut  of 
the  strawberry  tomato,  or  ground  cherry,  forms  whitish  or 
reddish  angular  spots  on  the  leaves  and  is  sometimes  so  abun- 
dant as  to  cause  serious  injury  to  the  foliage.  The  character 
of  the  host,  however,  makes  it  of  little  economic  importance. 

HAWTHOEN,  Cratcegns  sps. 

Leaf  Spot,  Entomosporium  ThiimenU  (Cke.)  Sacc.  This 
produces  small  angular  reddish  or  purplish  brown  spots  on  the 
leaves  of  the  English  hawthorn,  Crat<zgus  oxyacantha,  which 
is  sometimes  grown  in  yards. 

Rusts,  Gymnosporangium  macropus  Lk.,  G.  clavipes  C.  &  P. 
^cidial  stages  occur  on  leaves  of  cultivated  redhaws. 

HAZEL,  Corylus  sp. 

Black  Knot,  Cryptosporella  anomala  (Pk.)  Sacc.  Plate 
XVII,  c.  This  fungus  sometimes  becomes  very  injurious  to 
the  ornamental  cut  leaf  hazel.  In  one  nursery  it  proved  so 
destructive  that  the  owner  intended  giving  up  growing  this 
variety.'  The  black  knot  infects  the  branches,  breaking  out 
between  the  bark  as  oval  bodies  about  one-quarter  of  an  inch 
in  length,  in  the  surface  of  which  are  embedded  the  fruiting 
pustules. 

HICKORY,  Carya  alba. 

Anthracnose,  Gloeosporium  Caryce  Ell.  &  Dearn.  This 
forms  dark  purple  blotches  on  the  leaves. 


326        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

HOLLYHOCK,  Althasa  rosea. 

Leaf  Blight_,  Cercospora  althmna  Sacc.  The  numerous, 
small,  angular  spots  produced  on  the  leaves  by  this  fungus  are 
reddish  brown,  often  with  a  lighter  center. 

Leaf  Spot,  Ascochyta  parasitica  Fautr.  This  sometimes 
occurs  on  spots  associated  with  a  rust  pustule. 

Rust,  Puccinia  Malvacearum  Mont.  Plate  XVII,  d.  Rust 
is  the  most  common  trouble  of  hollyhocks  and  the  one  most 
frequently  sent  to  the  Station  for  determination.  The  fungus 
shows  as  roundish  cushions,  of  a  light  or  dark  red  color,  on 
both  leaves  and  stem.  Only  teleuto-spores  are  known  and  these 
germinate  in  position  so  that  the  pustules  are  often  covered  with 
a  whitish  growth  due  to  this  germination.  Some  think  the 
trouble  is  partially  controlled  by  spraying,  but  this  to  prove 
of  benefit  should  begin  before  the  appearance  of  the  rust  pus- 
tules. Possibly  the  trouble  might  be  checked  the  next  year,  if 
in  the  fall  the  plants  were  all  cut  off  below  the  ground  and  all 
of  the  rubbish  destroyed  by  fire.     [Rep.  1895,  p.  188.] 

HONEYSUCKLE,  Lonicera  sp. 

Powdery  Mildew,  Microsphcera  Lonicer^  (DC.)  Wint. 
Observed  occasionally  on  Tartarian  honeysuckles  in  old  gardens. 

HORSECHESTNUT,  ^scidus  Hippocastanum. 

Leaf  Spot,  Phyllosticta  Pavics  Desm.  A  very  serious  leaf 
trouble  of  the  cultivated  European  horsechestnut  is  caused  by 
this  fungus.  The  large  dark  red  blotches  often  reach  from  the 
margin  to  the  midrib  and  resemble  sunburn.  On  the  upper 
surface  the  minute  black  dots  of  the  fruiting  stage  are  often 
visible, 

HORSEEADISH,  Cochlearia  Armoracia. 

Leaf  Blight,  Ramularia  ArmoracicB  Fckl.  This  is  the 
fungus  ordinarily  reported  on  horseradish,  but  it  does  not  seem 
so  common  here  as  the  next  two.  The  spots  are  smaller  and 
paler  and  the  leaf  tissue  often  falls  out,  giving  a  shothole  effect. 

Leaf  Mold,  Macrosporitim  herculeiim  E.  &  M.  It  is  ques- 
tionable if  this  is  distinct  from  M.  Brassicce  var.  macrospora, 
which  is  reported  here  on  cabbage  and  other  cruciferous  plants. 


NOTES    ON    PARASITIC    FUNGI.  32/ 

This  can  usually  be  told  from  the  other  leaf  troubles  of  this 
host  by  the  brown  spots,  starting  as  black  dots,  forming  con- 
centric rings  of  development.  The  spots  are  about  one-quarter 
of  an  inch  in  diameter. 

Leaf  Spot,  Cercospora  Armoracia  Sacc.  Plate  XVII,  e. 
The  fruiting  stage  often  shows  as  an  inconspicuous  upright 
growth  on  the  surface  of  the  subcircular  brown  spots. 

INDIAN  CXJRRANT,  Symphoricarpus  vulgaris. 

Powdery  Mildew_,  Microsphcera  Symphoricarpi  Howe.  In 
nurseries  this  proves  a  common  trouble,  covering  the  upper  sur- 
face of  the  leaves  usually  with  a  dense  white  growth  of  the 
summer  spore  stage,  and  producing  an  abundance  of  the  peri- 
thecia  on  the  upper  surface  or,  more  scattered,  on  the  under  side 
of  the  leaves. 

mis,  Iris  sps. 

Leaf  Blight,  Heterosporium  gracile  (Wallr.)  Sacc.  This  is 
a  very  serious  trouble  of  the  Iris,  especially  of  Iris  Germanica. 
The  prominent  elliptical  spots  appear  scattered  over  the  leaves, 
.which  often  turn  yellowish  and  die  at  the  tips. 

Rootstock  Rot,  Bacteria.  Plate  XIX,  a.  In  one  of  the 
nurseries,  last  season,  this  trouble  was  common  on  Iris  Ger- 
manica and  /.  cristata.  Apparently  the  disease  had  been  greatly 
aggravated  by  burying  the  rootstocks  too  deeply  when  trans- 
planted that  spring".  The  wet  season,  too,  was  favorable  for 
the  development  of  the  trouble,  which,  according  to  the  manager, 
was  unusually  severe.  The  rootstocks  were  rotted  off  by  a 
wet  bacterial  rot,  which  sometimes  extended  up  into  the  base 
of  the  outer  leaves.  Apparently  this  is  the  same  trouble  that 
has  recently  been  described  from  Germany  [Zeitschr.  Pflanz- 
krankh.  13:  129-44,  1903.]  Dr.  van  Hall,  who  studied  the 
trouble  there,  found  three  organisms  associated  with  the  rot, 
of  which  Bacillus  omnivorus  apparently  was  the  chief.  The 
writer  made  no  cultural  studies. 

Rust,  Puccinia  Iridis  (DC.)  Wallr.  On  the  wild  species 
of  Iris  this  is  a  very  comrnon  rust,  but  it  was  found  only  once 
on  a  cultivated  species.  It  produces  the  ordinary  dusty  reddish 
pustules,  thickly  covering  the  leaves.  So  far  only  the  uredo- 
stage  {Uredo  Iridis  DC.)  has  been  found  here. 
22 


328        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I903. 

IVY,  BOSTON",  Ampelopsis  tricuspidata. 

Leaf  Spot,  Phyllosticta  Labrusccp  Thm.  This  is  apparently 
the  same  as  the  leaf  spot  form  of  black  rot  of  grapes. 

KCELRETJTERIA,  Kcelreuteria  paniculata. 

Red  Knot,  Nectria  cinnabarina  (Tode)  Fr.  Colortype  3. 
This  occurred  in  a  nursery  doing  serious  injury  to  this  Japanese 
tree.  On  the  sunken,  cankered  areas  reaching  clear  into  the 
wood,  there  was  found  an  abundance  of  the  small,  spherical, 
bright  red  perithecia  of  the  fungus.  There  was  some  question, 
however,  whether  winter  injury  did  not  form  the  starting  point 
of  the  trouble. 

LAVATERA,  Lavaiera  sp. 
Rust,  Puccinia  Malvacearum  Mont.     See  Hollyhock. 

LETTTJGE,  Lactiica  sativa. 

Downy  AIii.dew,  Bremia  Lactucce  Regel.  Lettuce,  both  in 
and  out  of  doors,  is  sometimes  bothered  by  this  fungus.  It 
produces  brownish  dead  areas  which  usually  show  on  the  under 
side  whitish  tufts  of  the  fertile  threads  of  the  fungus.  As  it 
is  a  trouble  that  thrives  best  in  moist  places,  care  in  watering 
greenhouse  plants  is  helpful  in  controlling  it.      [Bull.  142,  p.  9.] 

Grey  Mold,  Botrytis  vulgaris  Fr.  This  causes  a  rotting  or 
spotting  of  the  leaves,  upon  the  dead  portion  of  which  the 
fruiting  stage  develops  as  an  erect  greyish  mold.  It  is  common 
in  moist  greenhouses  and  is  apparently  the  same  Botrytis  that 
develops  on  a  great  variety  of  plants  under  moist  conditions. 
The  stem  rot  of  onions,  the  grey  mold  of  grapes  and  the  fruit 
mold  of  egg  plants  are  possibly  caused  by  different  species. 

Leaf  Spot,  Septoria  consimilis  Ell.  &  Mart.  This  can  be 
identified  by  the  fruiting  stage,  which  shows  as  very  small 
black  dots  in  the  spots  or  dead  areas  it  produces  on  the  leaves. 
Like  the  other  troubles,  care  in  watering  indoor  lettuce  and 
the  removal  of  diseased  leaves  as  soon  as  they  appear,  will  help 
to  keep  it  in  check.  It  will  pay  the  greenhouse  grower  never 
to  allow  any  wilted  or  dead  leaves  to  remain  either  on  the  plants 
or  on  the  soil. 


NOTES    ON    PARASITIC    FUNGI.  329 

LILAC,  Syringa  vulgaris. 

Powdery  Mildew^  Microsphcera  aim  (Wallr.)  Wint.  Every- 
one has  noticed  this  on  the  upper  surface  of  lilac  leaves.  Both 
spore  stages  are  produced  abundantly. 

LILY  OF  THE  VALLEY,   Convallaria  majalis. 

Leaf  Blotch.  During  the  summer  and  fall  the  leaves  of 
this  plant  commonly  become  discolored  with  purplish  blotches, 
which  often  run  together  into  large  areas.  So  far  no  fungus 
has  been  found  in  a  fruiting  condition  on  these  leaves,  but  the 
trouble  appears  to  be  of  fungous  origin. 

LILY,  WHITE  DAY,  Funkia  siihcordata. 

Anthracnose,  ?  Colletotrichum  sp.  Produces  subcircular 
brown  spots  with  purplish  borders. 

LINDEN,  Tilia  sp. 

Black  Mold^  Fwnago  vagans.  The  linden  trees  of  a  park 
in  Bridgeport  were  found  coated  on  their  upper  surface  with 
this  fungus,  which  gave  them  a  sooty  appearance. 

MAHONIA,  Mahonia  Japonica. 
Leaf  Spot,  Fhyllosficta  Japonica  Thm. 

MAPLE,  Acer  sps. 

Anthracnose,  Glceosporium  saccharini  E.  &  E.  Irregular 
dead  areas,  often  of  considerable  size,  are  produced  by  this 
fungus,  giving  the  appearance  of  sunburn. 

Black  Spot,  Rhytisma  acerinum  (Pers.)  Fr.  On  Acer 
dasycarpum.  This  forms  black,  slightly  elevated  "finger 
prints,"  about  y^  inch  wide,  on  the  upper  surface  of  the  leaves. 
The  lower  surface  is  often  concave  and  not  so  dark  colored. 
The  sac  fungus  producing  these  does  not  mature  its  spores 
until  some  time  after  the  leaves  have  fallen  from  the  trees. 

Leaf  Spot,  Fhyllosficta  minima  (B.  &  C.)  Ell.  (P.  acericola) 
On  Acer  dasycarpum,  A.  pseudoplatanus  var.  Causes  reddish 
or  brownish  circular  spots  about  %.  inch  in  diameter. 


330        CONNECTICUT   EXPERIMENT   STATION    REPORT,    I903, 

MARIGOLD,  Tagetes  sp. 

Grey  Mold,  Botrytis  vulgaris  Fr.  On  blossoms.  See 
Lettuce. 

MATRIMONY  VINE,  Lycnim  vulgare. 
Powdery  Mildew,  Erysiphecz  undet.     Conidia  only. 

MIGNONETTE,  Reseda  odorata. 

Leaf  Blight,  Cercospora  Resedce  Fckl.  Not  infrequently 
this  fungus  produces  small  whitish  spots  on  the  leaves. 

Stem  Rot,  Rhisoctonia  sp.  In  one  greenhouse  this  was 
found  doing  some  damage  to  the  plants.  The  stems  were  rotted 
off  at  the  base,  the  leaves  turning  yellowish.  Where  the  leaves 
came  in  contact  with  the  moist  ground,  they  also  started  to  rot. 

MUSK  MELON,  Cucumis  Melo. 

Anthracnose,  Collet otrichuni  Lagenarium  (Pass.)  Ell.  & 
Hals.     See  Watermelon, 

Downy  Mildew  (Blight),  Plasmopara  Cubensis  (B.  &  C.) 
Humph.  Plate  XVHI,  a-b.  This  trouble  has  been  prominent 
at  least  during  the  past  three  years,  though  last  year  it  was  not 
nearly  so  serious  as  the  year  before.  As  it  is  a  trouble  that 
comes  and  goes,  this  may  indicate  that  it  is  on  the  wane  again. 
The  disease  first  shows  during  the  latter  part  of  July  or  early 
August,  when  large,  brownish,  angular  spots  appear  on  the 
leaves.  If  the  season  is  favorable,  the  leaves  become  thickly 
covered  with  these,  the  intervening  green  tissue  dies  and  the 
leaf  dries  up  on  its  stalk.  In  a  very  few  days  the  trouble  may 
spread  so  rapidly  that  it  kills  practically  all  of  the  leaves.  This 
often  occurs  before  any  of  the  fruit  matures,  and  what  little 
does  ripen  lacks  flavor.  In  moist  weather,  by  looking  closely 
at  the  under  surface  of  the  leaves  with  a  magnifier,  the  fruiting 
threads  can  be  seen  at  the  juncture  of  the  green  and  dead 
tissue,  as  a  scanty,  dark  purple,  upright  growth.  The  color 
is  due  to  the  very  large  purplish  summer  spores  which  are 
borne  on  the  ends  of  these  fertile  threads.  The  winter,  or 
oospores,  have  never  been  found,  though  the  writer  has  searched 
for  them  at  all  seasons  of  the  year.  It  is  not  known  how  the 
fungus  passes  the  winter  in  this  state.     Possibly  it  does  not 


NOTES   ON    PARASITIC    FUNGI.  33 1 

winter  so  far  north,  or  possibly  it  is  carried  over  on  greenhouse 
cucumbers.  Any  curcubit  is  Hkely  to  be  attacked  by  it,  but  so 
far  it  has  been  observed  here  only  on  the  common  and 
English  cucumbers,  on  musk  melons  and  rarely  on  water- 
melons. During  seasons  when  the  trouble  develops  very  seri- 
ously, it  is  questionable  if  spraying  yields  any  very  striking 
results  with  musk  melons,  though  it  does  give  good  results 
with  cucumbers.  During  ordinary  seasons,  however,  this,  and 
most  of  the  other  troubles  of  the  musk  melon,  can  be  held  in 
check  by  thorough  and  repeated  sprayings  with  Bordeaux.  The 
first  application  should  be  made  as  soon  as  the  vines  begin  to 
run.     [Rep.  1899,  p.  2.^]^ ;  Bull.  142,  p.  10.] 

Leaf  Mold^  Alternaria  Brassicce  var.  nigrescens  Pegl.  {Mac- 
rosporium  cucumerinwn  Ell.  &  Ev.)  This  fungus  also  pro- 
duces brownish  spots  on  the  leaves  that  can  scarcely  be 
distinguished  by  the  naked  eye  from  those  of  the  preceding 
fungus.  It  occurs  also  on  the  watermelon.  While  not  an 
uncommon  trouble,  it  is  not  usually  so  serious  as  the  downy 
mildew.  The  treatment  is  the  same.  [Reps.  1895,  p.  186; 
1896,  p.  267;   1898,  p.  233;   1899,  p.  272;  Bull.  142,  p.  10.] 

Scab,  Cladosporium  cucumerinum  Ell.  &  Arth.  {Scoleco- 
trichum  melophthorimi  Pr.  &  Del.,  Cladosporium  cucumeris 
Frank.)  Plate  XIX,  b.  This  has  been  reported  several  times  in 
this  country  on  cucumbers,  and  in  Europe  on  both  cucumbers  and 
musk  melons.  Last  season  it  was  found  in  this  state,  on  both 
hosts,  but  doing  most  injury  to  melons.  It  appeared  about  the 
first  of  August,  producing  sunken  areas  on  both  stems  and  fruit. 
The  mycehum  produces  these  by  collapsing  the  tissues  and  then 
forms  on  the  outside  a  dense  olive  growth  of  a  summer  spore 
stage — the  only  one  known.  Apparently,  the  trouble  thrives 
only  in  very  moist  weather. 

Wilt,  Bacterial,  Bacillus  tracheiphilus  Sm.  Occasionally 
occurs,  doing  damage ;  see  Squash.  Bacteria  also  produce  a 
leaf  spot  trouble,  but  probably  this  is  only  another  form  of  the 
wilt  disease.     [Rep.  1898,  p.  225.] 

Wilt,  Fungus,  Neocosmospora  vasinfecta  (Atk.)  Sm.  In 
appearance  this  is  the  same  as  the  preceding,  but  the  Fusarium 
stage  of  the  Neocosmospora  fungus  clogs  up  the  water  ducts 
of  the  stem  and  produces  the  wilt.  Apparently  it  is  not  as 
common  as  the  bacterial  wilt.     [Rep.  1898,  p.  228.] 


332        CONNECTICUT    EXPERIMENT    STATION    REPORT^    IQOS- 

Spray  Injury.  Bordeaux  mixture  sometimes  slightly  injures 
the  foliage.  In  these  cases  the  leaves  turn  yellowish  at  the 
margin  and  may  die  prematurely  if  severely  injured.  Occa- 
sionally the  fruit  shows  some  distortion  or  the  scar  of  the 
blossom  end  becomes  greatly  exaggerated. 

Sun  Burn.  Sturgis  described  a  similar  trouble  which  he 
called  leaf  burn,  and  ascribed  to  a  sudden  disturbance  of  the 
equilibrium  between  water  absorption  and  evaporation.  "When 
cool,  cloudy  weather  alternates  with  hot  sunshine,  it  is  frequently 
noticed  that  the  large  leaves  near  the  center  of  the  hills  turn 
yellow  at  their  margin.  Later,  these  yellowed  margins  become 
brown  and  dry  and  finally  the  whole  leaf  is  diseased."  [Rep. 
1898,  p.  228.] 

MUSTARD,  Brassica  sp. 
Leaf  Mold,  Alternaria  Brassicce  (Berk.)Sacc.     See  Cabbage. 

OAK,  Querciis  sp. 

Powdery  Mildew,  Microsphcsra  quercina  (Schw.)  Burr. 
The  cultivated  English  oak,  Querciis  rohur,  frequently  has  this 
mildew  on  its  leaves. 

OAT  GrRASS,  Arrenathemm  avenaceum. 

Smut,  Ustilago  perennans  Rostr.  The  smut  destroys  the 
grain,  but  the  fungus  is  not  of  economic  importance  since  the 
host  is  rarely  grown  here. 

OATS,  Avena  sativa. 

Black  Stem  Rust,  Puccinia  graminis  Pers.  Plate  XIX,  c. 
This  rust  produces  elongated  outbreaks  on  the  stems  and  leaf 
sheaths.  These  are  at  first  the  reddish,  uredo-stage,  but  later  the 
black,  teleuto-stage.  The  stems  are  weakened  by  the  action  of 
the  fungus  and  badly  rusted  grain  is  apt  to  lodge.  The  bar- 
berry is  the  host  for  the  ascidial  stage,  but  apparently  the  fungus 
often  skips  this  step  in  its  life  cycle.  Black  rust  also  occurs 
here  on  red  top  and  timothy.  This  rust  very  commonly  occurs 
with  crown  rust,  and  the  injury  they  cause  to  the  crop  of  oats 
is  sometimes  considerable.  Very  little  can  be  done  to  lessen 
these  troubles.     [Rep.  1889,  p.  174.] 


NOTES    ON    PARASITIC    FUNGI.  333 

Crown  Rust,  Puccinia  coronata  Ccla.  Plate  XIX,  d.  This 
is  common  on  the  leaves,  producing  first  the  small,  dusty,  red 
uredo-stage,  and  later  the  blackish  teleuto-stage  firmly  imbedded 
in  the  tissues.  These  outbreaks  are  not  nearly  so  elongated  or 
prominent  as  in  the  preceding.  It  is  called  crown  rust  because 
the  teleuto-spores  have  curious,  horn-like  projections. 

Smut,  Ustilago  Avencs  (Pers.)  Jens.  Plate  XIX,  e.  This 
forms  the  common,  dusty,  blackish  masses  that  completely 
destroy  the  grain.  The  covered  smut,  Ustilago  levis,  less  com- 
pletely destroys  the  grain,  often  being  confined  to  the  inner  basal 
parts ;  neither  is  it  as  common  here,  -Both  of  these  smuts  can 
be  prevented  by  seed  treatment  with  formalin  or  hot  water. 
[Bull.  142,  p.  10.] 

ONION,  Allium  Cepa. 

Black  Mold,  Macrosporium  Porri  Ell.  Apparently  this  does 
more  or  less  damage  to  onions.  It  is  found  on  "blighted" 
onions  and  probably  is  partially  responsible  for  the  trouble. 
Thaxter  describes  and  figures  this  in  the  Report  for  1889,  p.  161. 
The  fungus  probably  belongs  under  the  genus  Alternaria  rather 
than  Macrosporium,  if  these  two  genera  are  distinct. 

Black  Spot,  V ermicularia  circinans  Berk.  Plate  XX,  a.  It 
is  on  the  stored  onions  that  this  trouble  becomes  prominent. 
Black  blotches,  made  up  of  the  small  black  fruiting  pustules, 
appear  on  the  outer  dry  coats  of  the  onion  and  gradually  work 
through  a  few  beneath.  While  not  causing  a  rot,  this  trouble 
seriously  affects  the  appearance  of  the  onion,  especially  the  white 
varieties,  and  thus  lessens  their  market  value.  So  far  the  only 
means  of  lessening  it  is  the  best  care  in  drying  and  storing  the 
crop.  Some  have  advocated  the  use  of  air-slaked  lime  scattered 
over  the  onions,  but  no  definite  experiment  has  been  undertaken 
to  show  the  value  of  this.     [Rep.  1889,  p.  163  ;  Bull.  142,  p.  11.] 

Downy  Mildew,  Peronospora  Schleideni  Ung.  Thaxter 
found  this  fungus  causing  serious  injury  to  the  onions  at 
AVethersfield  in  1889. "  It  has  not  been  seen  by  the  writer,  though 
it  probably  still  causes  trouble  occasionally.  Usually  the  whitish 
growth  of  the  mildew  is  not  very  prominent  and  may  be 
obscured  by  the  presence  of  the  black  'mold  fungi.  Through 
the  action  of  the  mycelium,  whitish  or  yellowish  spots  are  pro- 
duced in  the  tissues  and  the  injury  may  become  so  severe  that 


334        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

a  blighting  of  the  vines  results.  The  fungus  occurs  in  the  fields 
as  early  as  July.  Spraying  experiments  conducted  in  Vermont 
showed  that  the  trouble  could  be  partially  controlled  in  this  way. 

RoT_,  Bacterial.  Stored  onions  are  sometimes  destroyed  by  a 
soft  rot  due  to  bacteria.  Sometimes  the  whole  onion  rots  or 
only  certain  layers  may  go.  If  the  outer  ones  are  rotting,  they 
give  a  slippery  feeling  upon  pressure  with  the  hand.  Maggots 
often  accompany  or  follow  this  trouble. 

Smut,  Urocystis  Cepulce  Frost.  This  produces  black,  dusty 
pustules  on  the  leaves  and  bulbs.  It  may  be  found  early  in 
May  on  the  seedlings  or  late  in  the  fall  on  the  mature  bulbs. 
The  former  are  often  killed  outright  and  the  stand  seriously 
affected.  The  smut  may  become  established  in  the  soil  and  then 
it  becomes  more  and  more  difficult  to  raise  onions  on  this  land. 
Considerable  land  valuable  for  onion  culture  has  become  unavail- 
able for  this  purpose.  It  has  been  found  that  the  sets  do  not 
smut,  to  any  great  extent,  and  that  seed  onions  germinated  in 
free  soil  and  later  transplanted  to  the  infected  soil  also  remain 
nearly  free  from  smut  and  that  the  transplanting  increases  their 
size.  Preliminary  experiments  by  Thaxter  and  later  work  by 
Stewart,  of  New  York,  and  Selby,  of  Ohio,  show  that  the 
treatment  of  infected  soil  with  certain  chemicals  will  also  lessen 
the  amount  of  smut.  One  of  the  most  feasible  treatments  seems 
to  be  the  use  per  acre  of  lOO  lbs.  of  sulphur,  thoroughly  mixed 
with  50  lbs.  of  air-slaked  lime,  which  is  drilled  into  the  rows 
with  the  seed.  Another  remedy  is  sprinkling  formalin  over 
the  seed  before  covering.  Ground  lime,  drilled  into  the  soil  at 
the  rate  of  75  to  125  bushels  per  acre,  has  also  been  used. 
[Reps.  1889,  p.  129;  1890,  p.  103;  1893,  p.  99;  1895,  p.  176; 
Bull.  142,  p.  II.] 

Stem  Rot,  Botrytis  sp.  Plate  XX,  b-c.  In  Europe  tj;iere  is 
a  Botrytis  bulb  rot  of  onions  and  hyacinths  that  is  possibly 
the  same  as  that  described  here.  It  is  known  there  in  its  perfect 
stage  as  Sclerotinia  hulhorum.  This  trouble  has  occasionally 
occurred  in  Connecticut  before,  but  apparently  never  so  seriously 
as  during  the  past  two  years.  There  is  a  possibility  that  it  is 
not  specifically  different  from  the  common  Botrytis  trouble  of  our 
greenhouse  plants.  The  same  trouble  has  been  reported  before 
by  Halsted,  of  New  Jersey,  and  during  the  past  two  years  has 
occurred  also  in  Massachusetts  and,  perhaps,  elsewhere.     Only 


NOTES    ON    PARASITIC    FUNGI.  335 

the  Southport  White  Globe  seems  to  have  suffered  very  severely 
from  the  rot.  This  variety  is  largely  grown  in  Connecticut 
along  the  Sound  from  Green's  Farms  to  Guilford.  The  onion 
growers  of  Green's  Farms  and  Southport  have  suffered  espe- 
cially. In  1902  their  loss  was  estimated  at  least  $50,000,  and  in 
1903  the  crop  did  not  nearly  pay  expenses.  Some  growers 
stopped  sending  their  onions  to  market,  since  the  returns  per 
barrel  paid  little  more  than  the  freight.  One  grower  near 
Branford  was  able  to  market  only  about  400  bushels  out  of 
1,200  harvested,  but  these  brought  him  very  high  prices. 

The  stem  rot  does  not  appear  until  after  the  onions  are  stored 
in  the  fall.  Crops  tfiat  were  supposed  to  be  in  a  fair  shape 
when  stored  have  rapidly  disappeared  with  the  trouble  in 
October  and  later.  The  onions  are  sorted  and  the  good  ones 
sent  to  the  market,  but  apparently  these  rot  very  seriously  in 
transit.  The  trouble  is  called  stem  rot,  because  it  begins  at 
the  stem  end  of  the  onion,  which  becomes  soft  to  pressure  at 
this  place  due  to  the  rotting  of  the  inner  layers.  The  rot  does 
not  seem  to  usually  spread  from  onion  to  onion,  since  the  outer, 
drier  layers  are  generally  the  last  to  rot.  Plate  XX,  b,  shows 
the  top  view  of  a  rotting  onion,  while  a  cross  section  of  the 
same  onion  is  shown  in  Plate  XX,  c,  where  it  is  seen  that  only 
a  few  of  the  inner  layers  have  rotted.  Upon  the  exterior,  drier 
layers,  there  often  develops  a  dense  growth  of  the  olive-grey 
fertile  threads  of  the  summer  stage.  With  these  are  sometimes 
found  the  small  black  sclerotia,  or  resting  condition  of  the 
.mycelium,  that  carry  the  fungus  over  the  winter  and  apparently 
in  the  spring  develop  the  Botrytis  stage.  A  Sclerotina  or  asco- 
stage  has  not  been  seen  here.  According  to  the  writer's  observa- 
tions, this  fungus  in  its  Botrytis  stage  spreads  as  a  para'site  on 
the  green  leaves  and  on  the  blossoms  in  the  fields  as  early  in 
the  season  as  July.  It  causes  yellowish  spots  on  the  leaves 
and  blasts  the  flowers.  Wet  weather  is  especially  favorable 
for  its  development  and  this  accounts  for  the  unusual  injury 
during  the  past  two  seasons.  Wet  weather,  when  the  onions 
are  drying  in  the  field,  undoubtedly  is  very  favorable  for  the 
development  of  the  mycelium  into  the  bulbs  from  the  drying 
stems ;  however,  it  is  only  after  their  storage  that  the  real  stem 
rot  begins.  Probably  a  moist  fall  after  the  storage  also  aggra- 
vates the  trouble. 


336        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

So  far  no  remedies  have  been  tried  to  prevent  the  trouble. 
Unusual  care  in  curing  and  storing  the  crop  apparently  does  not 
stop  it.  The  character  of  the  land,  whether  new  or  old  in  onion 
culture,  seems  to  have  had  little  influence.  The  very  general 
prevalence  of  the  disease  points  to  the  wet  seasons  as  the  chief 
■factor  for  its  development, '  and  if  a  dry  season  should  now 
follow,  the  chances  are  that  the  trouble  would  lessen  very 
greatly.  Attention  should  be  called  to  the  old  rotting  onions 
as  a  means  of  carrying  the  fungus  over  the  winter  by  means 
of  the  black  sclerotia.  These  onions  should  not  be  used  as  a 
fertilizer  on  the  land.  The  fact  that  the  fungus  occurs  in 
summer  as  an  active  parasite  on  the  plants  indicates  that  pos- 
sibly sprkying,  by  keeping  the  plants  free  from  it  during  the 
growing  season,  may  lessen  the  chances  of  the  bulbs  rotting 
late.  If  onions  are  sprayed,  the  first  treatment  should  be  given 
very  early  in  July.  Resin  Bordeaux  will  probably  prove  the 
best  fungicide  to  use,  since  the  ordinary  Bordeaux  may  not 
adhere  readily  to  the  plants.  The  sprayings  should  be  repeated 
at  least  three  times.  This  treatment  is  recommended  only  as  a 
possible  remedy.     [Bull.  142,  p.  11.] 

Yellow  Leg  or  Black  Mold^  Macrosporium  parasiticum 
Thm.  This  trouble  is  caused  by  a  close  relative  of  the  fungus 
described  under  Black  Mold.  Thaxter  found  it  often  associated 
with  the  Downy  Mildew,  but  he  considered  it  a  true  parasite. 
It  was  found  in  1902  by  the  writer,  doing  considerable  damage 
to  seed  onions  in  the  vicinity  of  Milford.  Conspicuous  yel- 
lowish or  whitish  areas  are  produced  on  the  leaves  and  these , 
become  coated  with  a  luxuriant  black  growth  of  the  fruiting 
mold.     Spraying  ought  to  prevent  this  trouble. 

ORCHARD    GRASS,  Dactylis  glomerata. 

Ergot,  Claviceps  sp.  The  sclerotia  are  smaller  than  those  of 
the  rye  ergot. 

PARSLEY,  Petroselinum  sativum. 

Leaf  Spot,  Septoria  Petroselini  Desm.  Under  the  action  of 
this  fungus  the  leaves,  or  parts  of  them,  turn  whitish  and 
become  speckled  with  the  minute  black  spore  receptacles  imbed- 
ded in  the  tissues.  More  rarely  the  fungus  produces  distinct 
circular  whitish  spots  in  the  green  tissues.  A  variety  of  this 
fungus  occurs  on  celery. 


NOTES    ON    PARASITIC    FUNGI.  337 

PARSNIP,  Pastinaca  sativa. 

Leaf  Blght_,  Cercospora  Apii  var.  Pastinacce  Farl.  This 
is  only  a  variety  of  the  common  leaf  blight  of  celery.  It  has 
not  been  found  doing  any  considerable  injury  to  the  parsnip. 

PEA,  Pisum  sativum. 

Leaf  Spot,  Ascochyta  Pisi  Lib.  While  this  is  a  very  com- 
mon trouble  with  peas  it  is  only  occasionally  that  it  causes  severe 
injury.  Roundish  or  angular  spots  are  produced  on  both  the 
leaves  and  pods.  These  are  about  one-quarter  of  an  inch  or  less 
in  diameter  and  usually  have  a  distinct  narrow  purplish  border. 
[Rep.  1899,  p.  280.] 

Powdery  Mildew,  Erysiphe  Polygoni  DC.  The  powdery 
mildew  is  likely  to  be  found  on  the  peas  late  in  the  season  after 
they  have  passed  their  prime.  Sometimes,  however,  it  comes 
earlier  and  causes  more  severe  damage.  The  leaves,  stems  and 
fruit  become  coated  with  a  more  or  less  prominent  whitish  pow- 
dery coating  of  the  mycelium  and  summer  spores ;  later,  the 
small,  blackish  perithecia  of  the  asco-spores  are  produced. 
Spraying  with  potassium  sulphide  should  control  the  trouble. 

PEACH,  Prunus  Persica. 

Bacterial  Spot.  During  the  past  season,  leaves  of  peach 
were  received  from  an  orchard  in  Pomfret  that  were  covered  with 
small,  reddish  brown,  angular  spots  less  than  one-eighth  of  an 
inch  irf  diameter.  An  examination  of  the  diseased  tissues  under 
the  microscope  showed  an  abundance  of  bacteria,  which  were 
apparently  the  cause  of  the  trouble.  The  spots  were  very 
similar  to  those  produced  on  the  leaves  by  the  scab  fungus  or 
by  spraying  injury,  and  the  tissues  showed  a  tendency  to  fall 
out,  giving  a  shot-hole  effect.  As  1903  was  a  season  very 
favorable  for  the  development  of  bacterial  troubles,  in  normal 
seasons  this  bacterial  spot  may  not  prove  serious. 

Brown  Rot,  Sclerotinia  fructigena  (Pers.)  Schrt.  Plate 
XXI,  b.  The  fruit  is  the  part  of  the  host  most  severely  injured 
by  this  fungus.  About  the  time  of  ripening  it  may  begin  to 
decay,  and  if  the  weather  is  moist,  the  brown  rot  spreads  rapidly. 
The  ordinary  rot  of  the  peaches  bought  in  the  market  is  caused 
by  this   fungus.     The  brown   rotten  areas  rapidly  involve  the 


338         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O3. 

entire  peach,  and  the  summer  fruiting-  stage  usually  shows  in 
the  small,  dusty,  closely  packed  pustules  breaking  out  on  the 
surface.  The  disease  is  not  confined  to  the  fruit,  but  the  young 
twigs  and  sometimes  the  leaves  are  killed.  In  some  cases  the 
mycelium  apparently  passes  down  into  the  branches  from  the 
diseased  fruit.  In  wet  springs  the  fungus  also  sometimes 
blasts  the  blossoms.  Brown  rot  is  one  of  our  most  injurious 
fungous  foes,  since  in  wet  years  thousands  of  baskets  of  peaches 
are  destroyed  by  it.  Usually  it  is  most  troublesome  with  the 
early  varieties.  Plums  and  cherries  are  also  seriously  affected 
by  it,  while  apples,  quinces  and  pears  are  less  subject  to 
this  rot.  The  fungus  passes  the  winter  in  the  diseased  branches, 
and  also  in  the  mummied,  rotted  fruit;  the  mycelium  in  these 
giving  rise  to  new  summer  spores  in  the  spring.  Norton,  of 
the  Maryland  Experiment  Station,  has  recently  found  the 
mature  stage  of  the  fungus  developing  from  the  mummied  fruit 
buried  in  the  ground.  This  consists  of  a  narrow  pedicle  expand- 
ing above  the  ground  into  a  saucer-shaped  receptacle  that  con- 
tains the  winter  or  asco-spores.  This  then  is  another  means 
of  carrying  the  fungus  from  one  season  to  another.  So  far, 
this  stage  has  not  been  found  in  Connecticut. 

It  is  evident  that  all  rotten  fruit  should  be  destroyed  by  fire, 
and  that  all  mummies  should  be  carefully  removed  from  the 
trees  and  the  ground  each  season  after  the  harvest  time.  Dur- 
ing the  ripening  period,  all  rotten  fruit  should  be  gathered 
promptly,  in  order  to  check  the  spreading  of  the  trouble. 
Where  fruit  sets  very  abundantly,  the  common  practice  of 
thinning  also  serves  to  keep  down  the  trouble  later.  A  good 
many  spraying  experiments  to  prevent  brown  rot  have  been 
recorded,  some  of  which  evidently  have  proved  successful ;  but 
it  is  a  difficult  disease  to  combat  in  this  way,  both  because  of 
the  rapidity  with  which  it  spreads  in  moist  weather,  and  because 
of  the  injury  that  is  likely  to  result  to  the  foliage  from  the 
use  of  fungicides.  Where  spraying  is  to  be  tried,  perhaps  the 
best  treatment  would  be  a  winter  spraying  with  Bordeaux, 
given  as  for  leaf  curl,  followed  by  two  or  three  sprayings 
about  picking  time  with  potassium  sulphide  or  copper  acetate. 
[Reps.  1889,  p.  171  ;  1893,  p,  95;  1894,  p,  138;  1898,  p,  261; 
1900,  p.  232 ;   Bull.  142,  p.  12.] 

Crown  Gall,  Dendrophagus  globosus  Toum.     See  Plum. 


NOTES    ON    PARASITIC    FUNGI.  339 

Crown  or  Foot  Rot.  This  trouble  is  confined  to  the  region 
of  the  tree  near  the  juncture  of  the  stock  and  scion,  usually  just 
below  the  ground.  The  most  peculiar  character  is  the  ease  with 
which  the  trees  are  broken  off  at  this  place.  By  pushing  them 
from  side  to  side  by  hand,  they  will  often  crack  off  sharply  and 
sometimes  they  are  even  broken  off  by  the  winter  winds.  The 
trouble  is  not  usually  found  in  the  nursery,  but  it  has  been  seen 
in  young  orchards  only  set  out  one  or  two  years.  It  is  most 
conspicuous,  however,  in  the  older  orchards.  The  trunk  or 
roots  become  enlarged  at  the  crown,  so  that  it  is  sometimes 
called  "club  root."  Upon  breaking  off  the  trees  the  woody 
growth  is  seen  to  be  abnormal  here,  having  become  spongy 
and  brittle  and  thus  allowing  easy  fracture.  On  this  account 
it  is  known  also  as  "spongy  root."  The  cortex  is  abnormally 
developed  and  appears  diseased.  The  trees  usually  show  the 
trouble  some  years  before  dying.  They  cease  to  grow;  the 
foliage  gradually  becomes  scantier,  and  often  has  an  unhealthy 
appearance.  The  trouble  is  not  uncommon  in  the  peach  orchards 
of  the  state,  and  was  first  described  by  Sturgis  in  the  Report 
of  the  Pomological  Society  for  1901,  p.  235.  The  owner  of  one 
orchard  of  about  thirty  acres,  examined  by  the  writer,  stated  that 
he  had  removed  one  year  about  400  trees  and  since  then  a  few 
trees  had  been  taken  out  each  year.  It  is  a  question  whether 
the  trouble  is  contagious,  since  young  trees  set  out  in  the  place 
of  those  removed  do  not  seem  to  be  especially  troubled.  The 
cause  of  the  disease  is  not  surely  known.  Most  probably  it  is 
due  to  a  fungus  developing  in  the  bark  and  wood,  producing 
these  abnormal  and  diseased  conditions  of  the  tissues.  Sections 
of  the  cortex  have  shown  the  presence  of  mycelium  in  the  dis- 
eased tissues,  but  it  is  possible  that  this  may  have  come  in  late 
as  a  saprophyte.  The  other  possible  explanation  is  that  the 
morbid  conditions  result  from  too  great  moisture  in  summer, 
followed  by  injury  from  severe  cold  in  winter.  Most  growers 
remove  the  trees  as  soon  as  found  since  they  never  amount 
to  much. 

Dead  Limb  Fungus,  Cytospora  Persiccu  Schw.  This  fungus, 
apparently,  is  never  the  cause  of  disease,  but  it  is  frequently 
present  on  the  dead  limbs  as  a  saprophyte.  Sometimes  a  dead 
tree  is  entirely  covered  with  its  outbreaks.  These  show  as  small 
white  pustules. 


340        CONNECTICUT    EXPERmENT    STATION    REPORT,    I9O3. 

Leaf  Blight,  Cercosporclla  Persica  Sacc.  The  name  frosty 
mildew  describes  more  aptly  the  appearance  of  the  fungus.  It 
produces  yellowish  or  reddish  areas  on  the  leaves,  showing  the 
fruiting  condition  on  the  under  surface  usually  as  a  conspicuous 
white  growth.  Thaxter,  in  the  Report  for  1889,  p.  173,  records 
the  defoliation  of  orchard  trees  at  Deep  River  by  this  fungus. 
The  writer  has  observed  it  only  once,  where  it  was  doing  a 
little  damage  to  nursery  trees. 

Leaf  Curl,  Exoascus  deformans  (Berk.)  Fckl.  Colortype 
7.  Leaf  curl  is  one  of  the  earliest  appearing  diseases  of  the 
peach,  showing  soon  after  the  leaves  come  out.  It  kills  the 
entire  leaf,  or  the  greater  part  of  it,  usually  from  the  tip  down- 
ward. The  leaf  turns  yellowish  or  reddish  brown,  and  becomes 
more  or  less  irregularly  curled  or  wrinkled.  Often  a  whitish 
bloom  is  seen  on  the  diseased  area.  The  worst  infected  leaves 
drop  off,  so-  serious  defoliation  may  often  take  place.  The 
trouble  may  be  prevented  largely  by  a  single  spraying  with 
Bordeaux  mixture  just  before  the  buds  begin  to  swell  in  the 
spring.  In  very  wet  seasons  a  second  application,  with  the  half 
strength  mixture,  should  be  applied  just  after  the  petals  fall. 
The  winter  treatment  with  the  lime,  sulphur  and  salt  for  the 
scale  is  said  to  also  check  this  trouble  somewhat.  [Bull.  142, 
p.  12.] 

Powdery  Mildew,  Sphaerotheca  pannosa  (Wallr.)' Lev.  In 
nurseries  where  the  trees  are  crowded  closely  together,  this 
fungus  is  found  sometimes  causing  trouble.  Occasionally  it  is 
also  found  on  trees  in  the  orchard.  The  young  leaves  and  the 
twigs  become  covered  with  an  evident  white  felt  of  the  mycelium 
and  summer  spore  stage,  but  the  winter  stage  has  not  been 
observed.  Planting  the  trees  less  closely  would  no  doubt  be 
helpful  in  preventing  the  trouble  or  spraying  with  potassium 
sulphide  should  control  it. 

Scab,  Cladosporimn  carpophilum  Thm.  Plate  XXI,  a,  c-d. 
This  fungus  occurs  on  the  fruit,  leaves  and  twigs.  It  forms 
the  black,  circular,  superficial  spots  so  commonly  seen  on  the 
fruit  in  the  market.  Very  frequently  these  scabby  spots  pretty 
thoroughly  cover  one  half  the  surface,  that  which  faced  upwards 
on  the  tree.  When  abundantly  attacking  the  young  fruit,  it 
may  cause  it  to  develop  one-sided,  or  to  crack  open  when  mature, 
thus  exposing  it  to  decay  by  the  brown  rot  fungus.     On  the 


NOTES    ON    PARASITIC    FUNGI.  34 1 

leaves,  the  fungus  produces  a  reddish  brown  spotting  of  the  tis- 
sue, which  later  may  drop  out,  giving  a  shot-hole  effect.  On  the 
young  twigs  it  also  produces  conspicuous  reddish  brown  spots 
often  with  a  purplish  border.  The  mycelium  lives  over  the 
winter  on  the  infected  twigs  and  produces  the  summer  spores 
in  the  spring.  The  advantage  of  a  winter  or  early  spring 
treatment  on  the  dormant  tree  is  readily  seen.  Several  Con- 
necticut orchardists  report  less  scab  in  their  orchards  after  spray- 
ing with  the  lime,  sulphur  and  salt  mixture  for  the  San  Jose 
scale.  The  treatment  for  leaf  curl  should  also  be  of  benefit  for 
this  trouble.  Winter  treatment,  however,  will  not  wholly  stop 
it.  Taking  into  consideration  the  few  peaches  harvested  last 
year,  the  scab  was  more  injurious  than  usual.  [Reps.  1894, 
p.  138;  1896,  p.  269;  1898,  p.  261;  1900,  p.  232;  Bull.  142, 
p.  12.] 

Spray  Injury.  The  experiments  of  Sturgis,  Rep.  1900,  p. 
219,  showed  conclusively  that  there  was  danger  in  the  use  of 
fungicides  on  the  mature  foliage,  at  least  in  Connecticut. 
Bordeaux  mixture,  which  is  the  fungicide  commonly  used,  will 
produce  a  leaf-spotting  and  shot-hole  effect  very  like  that  of 
the  scab  fungus.  The  worst  injured  leaves  fall  off,  so  it  is 
possible  to  completely  defoliate  the  tree.  The  writer  found  that 
there  was  even  danger  in  the  use  of  the  half  strength  solution. 
Potassium  sulphide,  apparently,  is  the  safest  fungicide  to  use 
on  the  mature  leaves. 

Winter  Injury.  Plate  X,  a.  The  sudden  freeze  in  Decem- 
ber, 1902,  killed  the  fruit  buds  very  generally  and  also  injured 
the  wood  slightly.  This  darkening  of  the  wood  often  showed 
in  spots  in  a  cross  section  of  the  branch  and  became  more 
evident  toward  the  ends  of  the  twigs,  sometimes  ending  in  a 
dead  twig.  The  growth  of  new  wood  made  the  next  year  was 
good,  though  not  so  great  where  the  injury  was  very  manifest. 
The  winter  of  1903-4  was  very  much  more  injurious.  While 
the  trees  went  into  the  winter  in  better  condition  than  the  pre- 
vious year,  the  continued  and"  severely  cold  weather  made  its 
influence  felt  in  a  number  of  orchards.  The  injury  to  the 
fruit  buds,  apparently,  was  not  so  great  as  the  year  before.  The 
chief  injury  was  to  the  wood  of  the  trees;  this  showed  in  the 
blackening  or  darkening  of  the  wood  clear  down  to  the  snow 
line.     The  few  inches  of  the  trunk  next  the  ground,  protected 


342        CONNECTICUT    EXPERIMENT   STATION    REPORT^    I9O3. 

by  the  snow,  appeared  uninjured.  As  yet,  the  bark  does  not 
show  the  effect  of  this  injury,  and  no  cases  of  its  girdhng  was 
observed,  as  with  apples  the  previous  year.  Most  orchards 
escaped  this  injury,  while  others  in  the  same  locality  but  lower 
down,  were  very  severely  injured.  Many  trees  will  no  doubt 
have  to  be  cut  out ;  others  may  pull  through  with  a  severe  prun- 
ing. What  future  troubles  may  result  to  trees  severely  injured, 
if  left  standing,  is  not  known. 

Yellozvs.  This  is  now  considered  a  physiological  trouble,  due 
to  certain  enzyms  or  ferments  acting  on  the  tissues  and  dis- 
arranging their  normal  functions.  It  is  a  contagious  trouble. 
No  doubt  many  sickly  peach  trees  present  symptoms  that  may 
be  mistaken  for  yellows  by  some.  The  general  characters  of 
the  disease  are  as  follows :  A  premature  ripening  of  the  fruit, 
which  becomes  streaked  with  red  and  is  of  very  poor  quality; 
a  premature  development  of  the  winter  buds,  giving  rise  to 
excessive  branching  on  the  new  shoots ;  the  development  of 
adventitious  buds  into  elongated  sickly  water  sprouts ;  finally, 
a  scantier  and  sickly  yellowish  development  of  the  foliage.  The 
usual  method  followed  with  this  trouble  is  to  grub  out  the  trees 
as  soon  as  discovered,  and  plant  new  ones  in  their  places.  [Rep. 
1893,  p.  92;  Bull.  142,  p.  137.] 

PEAR,  Pirus  communis. 

Bitter  Rot,  Glomerella  rufomaculans  (Berk.)  Sp.  Sz:  von.  Schr, 
Occasionally  found  on  this  host  but  not  very  injurious.  See 
Apple. 

Black  Mold,  Fumago  vagans  Pers.  This  fungus  lives  in 
the  honey  dew  secreted  by  lice,  and,  while  often  forming  a 
conspicuous  coating  on  the  leaves,  it  is  hardly  to  be  feared  in 
itself.  Last  year  the  seasonal  conditions  were  unusually  favor- 
able for  the  propagation  of  the  pear  psylla  and  the  green  apple 
louse,  and  these  insects  did  serious  damage  to  their  hosts. 
Early  in  June,  developing  in  the  honey  dew  of  these  insects, 
there  appeared  on  the  pear  and  apple  leaves  and  twigs  a  con- 
spicuous coating  of  the  black  mold,  which  remained  prominent 
during  the  season.  Some  growers  mistook  this  for  the  cause 
of  the  injury,  which  really  resulted  from  the  attack  of  the  lice. 

Black  Rot,  Sphcsropsis  Malorum  Pk.  Occasionally  occurs 
on  twigs,  fruit  and  leaves.     See  Apple. 


NOTES    ON    PARASITIC    FUNGI.  343 

Brown  Rot,  Sclerotinia  fructigena  (Pers.)  Schrt.  Not  a 
very  serious  trouble  on  this  host.     See  Peach. 

Fire  Blight,  Bacillus  amylovorus  (Burr.)  De  Toni.  This 
bacterial  disease  is  the  most  serious  enemy  of  the  pear.  It  was 
with  this  that  bacteria  were  first  proved  to  be  the  agents  of 
disease  in  plants.  Insects  visiting  the  blossoms  accidentally 
carry  the  germs  to  the  nectar,  where  by  multiplication  they 
gradually  work  down  into  the  young  twigs  and  cause  their 
death  in  late  spring  or  early  summer.  Blighted  twigs,  a  foot 
or  two  in  length,  with  the  blackened,  dead  leaves  still  adhering, 
occur  commonly.  Cankered  areas  also  occur  in  the  bark  of 
the  older  branches  or  the  main  trunk.  Sometimes  sticky  exuda- 
tions of  the  bacteria  may  be  found  on  these  diseased  places, 
and  are  thus  exposed  to  distribution  by  insects.  Some  growers 
believe  that  blight  occurs  more  commonly  on  cultivated  trees 
than  those  left  in  sod.  The  only  treatment  is  thorough  prun- 
ing. This  should  be  done  in  winter,  when  the  germs  are  less 
likely  to  be  distributed,  and  care  should  be  taken  to  cut  off  the 
limbs  below  the  disease.  The  occasional  dipping  of  the  pruning 
knife  into  corrosive  sublimate,  to  kill  adhering  germs,  is  also 
advocated.  Cankered  areas  may  be  scraped  and  painted. 
Blight  occurs  also  on  the  quince,  apple  and  rarely  on  the  plum. 
[Rep.  1894,  p.  113;   Bull.  142,  p.  13.] 

Leaf  Blight,  Entomosporium  maciilatum  Lev.  Sometimes 
this  causes  serious  injury  to  the  leaves  and  fruit.     See  Quince. 

Leaf  Spot_,  Septoria  piricola  Desm.  So'  far,  this  has  been 
found  only  sparingly  here.  The  leaves  become  more  or  less 
covered  with  small,  greyish,  subcircular  or  angular  spots  with 
purplish  borders.  It  may  be  prevented  effectually  by  the  usual 
treatment  for  pear  scab.     [Bull.  142,  p.  13.] 

Pink  Mold,  Cephalothecuim  roseum  Cda.  Occasionally 
causes  rot  in  ripe  stored  pears.     See  Apple. 

Rust,  Gymnosporangium  glohosum  Farl.  Thaxter  reported 
the  secidial  stage  of  this  rust  [Rep.  1890,  p.  98]  on  Japanese 
varieties,  where  it  was  doing  considerable  damage.     See  Apple. 

Scab,  Venturia  pirina  (Lib.)  Aderh.  Like  apple  scab,  the 
parasitic  summer  stage  (Fusicladium  pirinum)  of  this  fungus 
is  now  known  to  be  connected  with  a  saprophytic  asco-spore 
stage  that  develops  on  fallen  leaves.  Pear  scab  is  closely  related 
to  apple  scab  and  very  similar  in  appearance,  and  the  treatment 

23 


344        CONNECTICUT   EXPERIMENT   STATION    REPORT^    1903- 

for  its  prevention  is  practically  the  same.     See  Apple.     [Reps. 

1889,  p.  173;   1893,  p.  73,  90;   1894,  p.  135;   Bull.  142,  p.  13.] 

Sooty  Blotch^  f  Phyllachora  pomigena  (Schw.)  Sacc.     This 

is  not  nearly  so  troublesome  on  the  pear  as  on  the  apple,  q.  v. 

PEONY,  PcBonia  sps. 

Scab,  Cladosporium  Pceonice  Pass.  This  trouble  forms  very 
conspicuous  blotches,  often  over  an  inch  in  diameter,  on  the 
leaves.  Usually  these  start  at  the  border  and  extend  inward. 
They  are  purplish  on  the  upper  surface  and  reddish  brown 
beneath.     It  was  found  once  doing  damage  in  a  nursery. 

PEPPERS,  Capsicum  annuum. 

Anthracnose,  Collet otrichum  nigrum  Ell.  &  Hals.  In  the 
Report  for  1899,  p.  282,  Sturgis  states  that  he  found  this 
fungus  destroying  25  per  cent,  of  the  fruit  in  certain  fields.  It 
develops  light  brown,  rotten  areas  on  the  fruit,  which  greatly 
enlarge  and  ruin  the  fruit.  The  fruiting  stage  shows  on  these 
rotten  spots  as  numerous  minute  black  pustules.  Spraying 
experiments,  conducted  by  Halsted,  of  New  Jersey,  did  not 
prevent  the  disease  very  successfully.  The  rotten  fruit,  as  soon 
as  it  appears,  should  be  picked  and  carried  away. 

Anthracnose,  Gloeosporium  piperatum  Ell.  &  Ev.  The 
writer  has  found  this  sparingly  in  the  fields.  It  produces  a  rot 
of  the  fruit  like  the  above,  but  the  fruiting  stage  shows  as 
minute  pinkish  globules. 

Black  Mold,  Macrosporium  commune  Rabh.  On  the  rotten 
areas  of  the  fruit,  one  sometimes  finds  this  fungus  developing 
a  luxuriant  olive-black  moldy  growth.  Apparently,  it  is  only  a 
saprophyte. 

Grey  Mold,  Botrytis  sp.  The  grey  mold  that  affects  a  great 
variety  of  plants  also  produces  rot  on  the  peppers,  and  develops 
a  dense,  erect  growth  of  the  olive-grey  fruiting  threads  on  them 
in  moist  weather. 

PHLOX,  Phlox  sps. 

Leaf  Blight,  Septoria  sp.  Forms  large,  irregular,  whitish 
areas  in  which  are  thickly  embedded  the  small  black  spore 
receptacles. 


NOTES    ON    PARASITIC    FUNGI.  345 

Leaf  Spot^  Cercospora  omphacodes  Ell.  &  Holw.  Forms 
small  whitish  spots  with  purplish  borders. 

Powdery  Mildew^  Erysiphe  cichoracearum  DC.  Plate 
XXIV,  a.  This  is  a  common  trouble  with  phlox,  the  mycelium 
thickly  coating  the  stem  and  leaves.  Both  spore  stages  occur. 
The  trouble  could  probably  be  kept  in  check  by  spraying. 

PINK,    SWEET    WILLIAM,  Dianthus  barbatus. 
Stem  Rot^  Rhizoctonia  sp.     See  Platycodon. 

PLATYCODOIT,  Platycodon  grandiflorum. 

Stem  Rot,  Rhizoctonia  sp.  The  stems  gradually  rot  at  the 
ground,  and  the  plants  wilt  and  often  die  as  the  result.  The 
fungus  lives  in  the  soil  and  appears  year  after  year,  killing 
some  of  the  stems.  The  trouble  may  spread  to  neighboring 
plants,  as  it  occurs  on  Sweet  William,  mignonette,  carnations,  etc. 

PLTJM,  Prunus  sps. 

Black  Knot,  Plowrightia  morbosa  (Schw.)  Sacc.--  Plate 
XXIV,  c.  The  black,  gall-like  excrescences  that  occur  on  the 
limbs  are  familiar  to  every  one.  Ordinarily,  they  form  an 
elongated  irregular  enlargement  two  or  three  times  the  thickness 
of  the  small  branch.  The  surface  is  very  uneven  with  minute 
elevations,  indicating  the  spore  cavities.  The  knots  sometimes 
attain  considerable  size  or  produce  distortion  in  the  large 
branches.  By  the  thorough  pruning  of  affected  branches,  the 
trouble  can  be  held  in  check.  In  the  nursery  this  can  be  supple- 
mented with  spraying.  The  mycelium  penetrates  deeply  into 
the  wood  and  causes  dark  streaks;  in  pruning,  all  this  should 
be  removed.  Where  large  branches  are  removed,  it  is  best  to 
paint  over  the  cut  surfaces.  In  some  cases  entire  trees  need  to 
be  cut  down.  The  Japanese  varieties  now  seem  to  knot  as 
badly  as  any  of  the  others.  Wild  and  cultivated  plums  and 
wild  cherries  are  subject  to  the  same  trouble.  While  always 
present,  it  seems  to  have  developed  more  vigorously  than  usual 
during  the  past  two  years.  [Reps.  1889,  p.  176;  1893,  p.  94; 
Bull.  142,  p.  6.] 

Brown  Rot,  Sclerotinia  fructigena  (Pers.)  Schrt.  A  serious 
trouble  of  this  host.     See  Peach.     [Rep.  1889,  p.  176.] 


346        CONNECTICUT   EXPERIMENT   STATION    REPORT,    I903. 

Crown  Gall_,  Dendrophagus  blobosus  Toum.  Plate  XXIV,  b. 
So  far  this  has  been  found  here  chiefly  in  nurseries.  The  gahs 
are  usually  on  the  lower  part  of  the  stem  near  the  ground,  or 
on  the  roots.  They  are  morbid  outgrowths  of  the  tissues, 
usually  subspherical  in  shape  and  about  an  inch  or  two  in  diame- 
ter. Sometimes  they  practically  encircle  the  crown,  girdling 
the  tree.  Professor  Toumey  made  a  study  of  this  trouble  on 
the  almond  in  Arizona  and  ascribed  it  to  a  new  species  of 
slime  mold.  Nursery  stock  showing  any  signs  of  these  galls 
should  be  rejected.  The  same  trouble  is  found  here  in  nurseries 
on  the  peach,  and  the  same  or  similar  troubles  occur  on  rasp- 
berry and  apple.      [Bull.  142,  p.  14.] 

Fire  Blight,  Bacillus  amylovorus  (Burr.)  DeToni.  In  the 
Report  for  1894,  p.  117,  Sturgis  described  a  bacterial  trouble 
of  plums  found  doing  damage  in  an  orchard  at  Hartford.  It 
was  not  known  at  that  time  whether  the  trouble  was  the  same 
as  pear  blight,  but  later  study  by  Jones,  of  Vermont,  seems  to 
show  the  identity  of  the  two. 

Leaf  Curl,  Exoasctis  mirabilis  Atk.  Sturgis  records  this  as 
doing,  damage  in  an  orchard  in  New  London  in  1895.  The 
trouble  is  somewhat  similar  to  peach  curl,  except  the  young 
branch,  as  "  well  as  the  leaves,  becomes  distorted  into  an 
irregularly  thickened  body.  The  injury  to  the  leaves  usually 
extends  from  the  base  up.  The  same  treatment  given  for  peach 
curl  should  be  used  for  this. 

Leaf  Spot,  Cylindrosporium  Padi  Karst.  This  does  not 
occur  so  commonly  on  the  plum  as  on  the  cherry,  q.  v. 

Plum  Pocket,  Exoascus  Pruni  Fckl.  So  far  this  has  not 
been  recorded  from  this  state,  but  is  included  here  in  the  hope 
that  some  one  will  send  in  specimens.  It  is  caused  by  one  of 
the  curl  fungi,  which  attacks  the  young  plums,  forming  elon- 
gated, inflated  bodies. 

Powdery  Mildew,  Podosphcera  oxyacanthce  (DC.)  DeBy. 
So  far  this  mildew  has  been  found  only  in  its  conidial  form, 
producing  whitish  growth  on  the  leaves.  Apparently  it  is  not 
common. 

Scab,  Cladosporium  carpophilum  Thm.  This  has  been  found 
here  only  on  wild  plums,  but  no  doubt  it  occurs  occasionally 
on  the  cultivated  sorts.     See  Peach. 

Shot-hole.     Spraying  and  certain  fungi  may  produce  shot- 


NOTES    ON    PARASITIC    FUNGI.  34/ 

hole  troubles  in  the  foliage  of  plums,  but  in  most  of  the  cases 
examined  these  seemed  to  have  had  other  agents ;  at  least,  the 
trees  were  not  sprayed  and  no  signs  of  a  fungous  agent  were 
found.  Insects  are  probably  responsible  in  some  cases,  and  it  is 
barely  possible  that,  as  in  the  case  of  the  peach,  bacteria  cause 
the  trouble.  Some  botanists  have  attributed  it  at  times  to 
weather  conditions.  The  plum  seems  to  resent  any  injury  to 
the  foliage  by  dropping  out  the  injured  tissue. 

POPLAR,  Populus  sps. 

Anthracnose,  Marsonia  Castagnei  (Desm.  &  Mont.)  Sacc. 
The  white  poplar,  Populus  alba,  is  attacked  by  this  fungus.  It 
produces  reddish  brown,  subcircular  spots  on  the  upper  surface 
of  the  leaves ;  the  spots  may  become  so  numerous  that  they 
merge  into  one  another.  The  spores  ooze  out  through  very 
small  rifts  in  these  spots. 

Canker.  Nurserymen  complain  .of  a  trouble  of  the  Carolina 
poplar  that  is  apparently  of  fungous  origin  and  produces  can- 
kered places  in  the  bark  and  wood,  especially  at  the  base  of  the 
young  branches. 

Rust,  Melampsora  populina  (Jacq.)  Lev.  This  is  a  common 
trouble  occurring  on  the  leaves  of  a  number  of  the  poplars.  The 
uredo-spores  break  out  as  dusty,  reddish  pustules,  but  the  teleuto- 
spores  are  permanently  embedded  in  the  tissues  and  mature  often 
after  the  leaves  fall  to  the  ground. 

POTATO,  Solanum  tuberosum. 

Anthracnose,  V ermicularia  sp.  After  potato  vines  die, 
especially  if  blighted,  this  common  saprophytic  fungus  almost 
always  appears  on  the  stems,  showing  its  fruiting  stage  in 
numerous,  minute  black  tufts. 

Blight  or  Downy  Mildew,  Phyfophthora  infestans  DeBy. 
Plates  XXII,  d,  XXIII,  a-b.  Any  dead  potato  vine  is  likely 
to  ,be  called  blighted  by  the  general  observer.  This  trouble, 
however,  does  not  appear,  usually,  until  about  the  middle  of 
July  or  later.  Wet  weather,  of  several  days  duration,  any  time 
from  the  first  part  of  July  till  the  middle  of  August  is  very 
likely  to  bring  it  into  prominence,  whole  green  fields  suddenly 
turning  brown,  the  vines  dying  in  a  few  da3's.  A  careful  exam- 
ination of  these  fields,  however,  would  show  its  presence,  in 


348        CONNECTICUT   EXPERIMENT   STATION    REPORT^    I903. 

an  inconspicuous  way,  some  time  before  this.  At  first,  prom- 
inent black  spots  appear  at  the  tips  or  margins  of  the  leaves. 
Careful  examination  on  the  under  side  shows  a  slight  whitish 
growth  at  the  juncture  of  the  green  and  diseased  tissue.  This 
is  the  summer  spore  stage  of  the  fungus,  and  it  is  by  the  quick 
germination  of  the  spores,  in  drops  of  moisture,  that  the  disease 
rapidly  spreads.  The  black  spots  soon  envelop  the  whole  leaf- 
let, the  leaves  die,  and  soon  there  remain  only  the  upright 
stems  bearing  the  inconspicuous  dried  up  foliage.  The  fungus 
occasionally  appears  on  the  green  stems,  but  usually  these  die 
only  as  the  result  of  the  death  of  the  leaves.  The  writer  has 
rarely  found  the  fungus  on  the  tubers,  but  it  apparently  passes 
the  winter  in  them,  since  the  mature  or  oospore  stage  has  never 
been  surely  found.  The  rotting  of  the  tubers  may  or  may  not 
follow  the  blighting  of  the  vines.  This  rotting,  apparently,  is 
due  to  other  agents;,  namely,  bacteria  and  the  Fusarium  fun- 
gus, q.  V. 

By  thoroughly  spraying  the  vines  with  Bordeaux  mixture, 
the  blight  can  be  largely  prevented,  or  so  delayed  that  the  yield 
of  tubers  is  greatly  increased  over  that  of  unsprayed  fields. 
The  writer  has  this  subject  under  investigation  to  determine, 
if  year  after  year,  spraying  potato  fields  in  Connecticut  is  a 
paying  operation.  The  results  of  two  years  work  indicate  that 
it  is  profitable  when  the  work  is  done  thoroughly  and  on  time. 
In  one  case  the  sprayed  rows  gave  twice  the  yield  of  those 
unsprayed ;  in  another  case  the  yield  was  a  third  greater ;  in 
a  third  case,  where  the  vines  were  very  imperfectly  sprayed, 
the  increase,  if  any,  was  lost  through  rotting.  The  first  spray- 
ing should  be  given  before  the  first  appearance  of  the  trouble, 
about  the  7th  to  the  15th  of  July,  according  to  the  season;  the 
second  and  the  third  should  follow  as  the  sediment  wears  off 
the  leaves.  If  rightly  placed,  three  sprayings  will  ordinarily 
suffice,  but  the  vines  should  be  well  protected  by  the  sediment 
until  about  the  first  of  September.  It  is  very  important  that 
the  vines  be  thoroughly  covered  with  the  spray  when  the  blight 
zveather  comes  on  and  it  is  usually  best  to  immediately  follow 
this  weather  with  another  spraying.  The  best  apparatus  for 
spraying  is  a  two-wheeled  cart  or  light  wagon  that  will  straddle 
two  rows,  allowing  the  horse  to  walk  between,  and  the  com- 
mon barrel  spray  pump  mounted  in  it,   having  two  leads  of 


NOTES   ON    PARASITIC    FUNGI.  349 

sixteen  foot  hose  provided  with  double  nozzles.  One  man 
drives  and  pumps,  and  two  men  follow  behind  the  cart,  each 
spraying  three  or  four  rows.  The  foliage  should  be  well 
drenched  with  the  mixture,  using  two  or  three  barrels  per  acre. 
In  the  writer's  experience,  geared  power  sprayers  are  not  satis- 
factory, since  with  these  the  foliage  can  not  be  properly  covered 
with  the  spray.  [Reps.  1889,  p.  173,  176;  1890,  p.  102;  1892, 
P-  39;    1893.  P-  7Z,  100;   Bull.  142,  p.  15.] 

Dry  Rot,  Fusarium  oxysporum  Schl.  (F.  Solani  (Mart.) 
Sacc.)  Plate  XXII,  b.  Smith  and  Swingle,  of  the  United 
States  Department  of  Agriculture,  have  lately  shown  this  fun- 
gus to  be  responsible  for  a  wilt  of  vines,  and  for  end  rot  and  the 
bundle  blackening  of  the  tubers.  During  the  past  season,  many 
vines  wilted  in  this  state  before  the  middle  of  July.  Possibly 
this  was  caused  by  the  fungus  described  here.  After  the  downy 
mildew  killed  the  vines,  there  was  general  complaint  of  rotting 
tubers,  and  the  dry  rot  fungus,  unquestionably,  was  partially 
responsible  for  this.  The  rot  did  not  do  much  damage  until 
after  the  vines  were  blighted,  for  very  few  of  the  potatoes  dug 
immediately  after  the  vines  blighted  were  rotted,  while  in  adja- 
cent rows,  dug  two  weeks  later,  very  many  were  rotten.  There 
was  a  great  difference  in  the  amount  of  rot  in  different  fields,  and 
even  in  different  parts  of  the  same  field.  During  the  past 
winter,  the  market  potatoes  have  shown  an  unusual  amount  of 
end  rot  and  the  bundle  blackening.  Sometimes,  these  potatoes 
appear  perfectly  sound  on  the  outside.  Usually  the  end  rot 
begins  at  the  stem  end  and  gradually  rots  the  tuber,  often  show- 
ing the  fungus  as  a  whitish  mold  on  the  outside.  The  potato 
shown  in  Plate  XXII,  b,  was  one  taken  from  the  field  and  placed 
for  a  day  or  two  in  a  moist  chamber  to  develop  the  growth 
of  the  mold  on  the  outside,  so  it  shows  this  more  prominently. 
Care  in  selecting  seed  potatoes  free  from  this  trouble  and 
spraying  thoroughly  for  the  blight  are,  perhaps,  the  best  methods 
for  lessening  the  trouble.  Season,  in  some  way,  seems  to  be  an 
important  factor  in  determining  the  amount  of  rot,  since  in 
1902  there  was  little  of  this  trouble,  while  in  1903  it  was  very 
common,  yet,  both  years  the  vines  blighted.  Apparently,  wet 
weather,  after  the  vines  blight,  develops  the  trouble  most 
vigorously. 

Early  Blight,  Alternaria  Solani  (E.  &  M.)  J.  &  Gr.  This 
trouble  produces  distinct,  subcircular,  brown  spots  about  one- 


350        CONNECTICUT    EXPERIMENT    STATION    REPORT^    IQOS- 

fourth  of  an  inch  in  diameter  on  the  leaves.  The  spots  often 
show  faint  concentric  rings  of  development.  Paris  green  may 
burn  spots  on  the  foliage  so  similar  to  these  that  the  two 
injuries  are  not  easily  distinguished.  So  far  as  observed  by 
the  writer,  this  trouble  has  not  proved  very  serious  in  this  state. 
It  usually  appears  early  in  the  year,  and  is  most  common  in 
moist  seasons.     The  tomato  and  egg  plant  are  also  hosts  for  it. 

Rosette^  Corticium  vagum  var.  Solani  Burt.  So  far  the 
writer  has  not  found  this  doing  serious  damage  in  Connecticut, 
though  it  has  been  very  injurious  in  several  other  states.  The 
trouble  appears  early  in  the  season,  dwarfing  the  vines  or  caus- 
ing the  foliage  to  become  crowded  into  rosette  clusters.  Badly 
infected  vines  may  be  killed  outright.  It  is  caused  by  the  sterile 
mycelium  (called  Rhisocfonia)  of  this  fungus,  producing  cank- 
ered or  dead  areas  on  the  stems  near  the  ground.  The  plants 
sometimes  send  out  new  roots  above  these  girdled  places ;  but 
the  effect  in  any  case  is  to  produce  a  crop  of  small  potatoes. 
Selection  of  good  seed  tubers  followed  with  treatment  in  forma- 
lin will  prevent  the  disease  if  the  potatoes  are  planted  in  unin- 
fected soil. 

ScAB_,  Oospora  scabies  Thaxt.  Plate  XXII,  c.  Professor 
Thaxter,  while  botanist  of  this  Station,  first  found  the  cause 
of  the  scabby  or  superficially  corroded  condition  of  potatoes  so 
common  everywhere.  This  is  due  to  a  fungus,  which  on 
freshly  dug  potatoes  sometimes  shows  as  a  slight  whitish  mold 
on  the  scabby  places.  It  is  known  that  this  fungus  becomes 
established  in  the  soil  and  the  use  of  manure  was  shown  by 
Sturgis  to  greatly  increase  the  number  of  scabby  tubers.  Seed 
treatment  with  corrosive  sublimate  or  formalin  (see  page  295  of 
this  report  for  directions)  will  prevent  the  scab  if  the  treated 
potatoes  are  planted  on  uninfected  land.  Beets,  turnips,  etc.,  are 
also  subject  to  scab.  [Reps.  1877,  p.  68;  1886,  p.  79;  1890, 
p.  81;  1891,  p.  153;  1893,  p.  102;  1894,  p.  118;  1895,  p.  166; 
1896,  p.  246;   Bull.  103,  p.  3;    142,  p.  15.] 

Wet  Rot,  Bacterial.  Plate  XXII,  a.  Durin'g  the  past  sea- 
son this  trouble,  together  with  the  dry  rot  fungus,  caused  serious 
rotting'  of  the  tubers.  The  bacterial  rot  can  be  told  from  the 
dry  end  rot  by  the  slimy  rotten  condition  of  the  tissues  and 
the  very  strong  odor.  Sometimes  the  same  tuber  has  both 
agents  at  work.  The  season  early  in  1903  was  very  unfavorable 
for  potatoes.     This  was  due  to  the  very  dry  May,  followed  by 


NOTES    ON    PARASITIC    FUNGI.  35 1 

a  very  wet  June.  In  some  fields,  as  a  result  of  these  conditions, 
a  bacterial  rot  of  the  young  stems  developed,  starting  usually 
below  the  ground  and  coming  possibly  from  the  decayed  tubers. 
It  produced  a  black  and  often  soft  rot  of  the  tissues  of  the 
stem  and  caused  the  wilting,  yellowing  or  death  of  the  parts 
above.  This  trouble  was  found  worse  in  one  field  that  had  been 
planted  to  potatoes  immediately  after  plowing  under  green  rye. 
The  stand  obtained  in  this  field  was  very  irregular,  and  in  the 
fall  the  tubers  were  found  badly  rotted  from  the  bacterial  wet 
rot.  Very  probably  the  bacterial  troubles  of  the  vines  early  in 
the  season  and  of  the  tubers  later  were  caused  by  the  same 
organism,  though  no  experiments  were  undertaken  to  prove  this. 

Paris  Green  Burn.  Potato  foliage  is  very  often  burned  by 
the  use  of  too  much  Paris  green  or  by  its  use  without  lime  to 
neutralize  its  caustic  effects.  The  injury  may  occur  as  distinct 
roundish  spots',  or  it  may  show  as  a  general  searing  of  the  mar- 
gins, which  die  and  dry  up. 

Tip  Biirn.  Dry  warm  weather  of  midsummer  may  cause 
many  of  the  leaves  to  die  at  their  margins,  which  become  dry 
and  rolled  up,  because  the  leaves  are  not  able  to  check  or  replace 
sufficiently  the  water  lost  through  transpiration.  It  is  a  trouble, 
however,  that  is  more  common  and  injurious  in  the  drier  states 
of  the  Mississippi  valley. 

PRIMROSE,  Primula  sp. 
Grey  Mold,  Botrytis  vulgaris  Fr.     See  Lettuce. 

PRIVET,  Ligustrum  Japonicum. 

Winter  Injury.  The  freeze  of  December  9,  1902,  seriously 
injured  the  California  privet  by  killing  the  branches.  Very 
few  plants  were  killed  outright,  so  that  with  vigorous  pruning 
the  injured  spots  in  the  hedges  were  gradually  obliterated  dur- 
ing the  growing  season. 

PUMPKIN,  Cucurhita  sps. 

Powdery  Mildew,  Erysiphe  cichoracearum  DC.  The  coni- 
dial  stage  of  this  fungus  occurs  as  a  scanty  whitish  growth,  in 
patches  on  the  upper  surface  of  the  leaves.  Apparently,  it  does 
little  injury.  No  doubt,  most  of  the  troubles  recorded  here  under 
squash  also  occur  on  pumpkins  but  were  not  observed. 


352        CONNECTICUT   EXPERIMENT   STATION    REPORT,    I903. 

QTTINCE,  Pirus  Cydonia. 

Black  Rot,  Sphm-opsis  Malorum  Pk.  This  often  causes 
serious  rotting  of  the  fruit  as  it  nears  maturity,  usually  starting 
at  the  exposed  blossom  end.  See  Apple.  [Reps.  1892,  p.  43; 
1893,  p.  78;   Bull.  142,  p.  15.] 

Brown  Rot,  Sclerotinia  fructigena  (Pers.)  Schrt.  This  is 
another  fungus  that  produces  rot  in  the  ripening  fruit,  though 
it  is  not  nearly  so  injurious  to  this  host  as  to  the  peach,  q.  v. 

Fire  Blight,  Bacillus  amylovorous  ( Burr. )  DeToni.  Blight 
is  very  common  on  the  quince.  The  leaves  adhering  to  the  dead 
twigs  have  a  decided  reddish  brown  color,  quite  different  from 
the  blackened  leaves  produced  on  the  pear,  q.  v. 

Leaf  Blight,  Entomosporium  maculatum  Lev.  So  far  the 
writer  has  observed  this  trouble  only  on  the  leaves  and  the 
fruit.  It  is  one  of  the  most  common  and  serious  troubles  of 
this  host.  On  the  leaves  it  produces  small,  circular,  brownish 
spots,  often  showing  the  fruiting  body  as  a  black  dot  in  the 
center.  When  the  leaves  are  badly  infested,  complete  defolia- 
tion may  result  before  the  end  of  the  season.  On  the  fruit,  the 
fungus  produces  a  black  spotting,  and,  especially  with  pears, 
may  cause  it  to  grow  one-sided  or  crack  open.  Thaxter  was 
one  of  the  first  to  successfully  prevent  this  trouble  by  spraying. 
Bordeaux  mixture  should  be  applied,  first  just  before  the  blos- 
soms open,  again  after  they  fall  and  a  third  and  fourth  time 
at  intervals  of  about  two  or  three  weeks,  according  to  the 
weather.  [Reps.  1889,  p.  173;  1890,  p.  99;  1891,  p.  150; 
1892,  p.  42;   1893,  p.  89,  91 ;  Bull.  142,  p.  13,  15.] 

Leaf  Spot,  Hendersonia  Cydonice  Cke.  &  Ell.  Occasionally 
this  fungus  occurs  in  spots  on  the  leaves.  Sometimes  it  may 
cause  these,  but  often  it  merely  develops  on  spots  produced  by 
the  black  rot  fungus.     [Rep.  1893,  p.  81.] 

Rusts,  Gymnosporangium  glohosum  Farl.,  G.  nidus-avis 
Thaxt.,  G.  clavipes  Cke.  &  Pk.  The  secidial  or  cluster-cup 
stages  of  these  rusts  were  reported  by  Thaxter  and  Sturgis  on 
the  leaves  and  fruit  of  quince.  Sometimes  they  cause  serious 
injury  to  this  host.     See  Apple.     [Reps.  1891,  p.  161 ;    1894, 

p.  I37-] 

Scab,  Fusicladium  sp.  In  the  Report  for  1893,  p.  79,  Sturgis 
records  the  occurrence  of  a  destructive  fungus,  similar  to  apple 
scab,  on  the  leaves  of  quinces  at  Tolland.  The  fungus  was 
not  specifically  determined  and  has  not  been  reported  since. 


'       NOTES   ON    PARASITIC   FUNGI.  353 

RADISH^  Raphanus  sativus. 

Downy  Mildew,  Peronospora  parasitica  (Pers.)  Tul.  See 
Turnip. 

Leaf  Mold^  Alternaria  Brassicce  var.  macrospora  Sacc.  This 
forms  numerous,  small,  blackish  spots  on  the  leaves  and  the 
diseased  tissue  sometimes  drops  out.  The  smallest  spots  look 
like  insect  punctures.     See  Cabbage. 

White  Rust,  Albugo  candidus  (Pers.)  Ktze.  The  small, 
white  blisters  are  formed  on  the  under  side  of  the  leaves. 
Upon  rupture  of  the  covering  epidermis  the  spores  are  gradually 
shed  out  as  a  dusty  powder.  While  this  fungus  belongs  with 
the  downy  mildews,  its  gross  and  microscopic  characters  are 
quite  different,  except  with  the  winter  spores.  It  probably 
occurs  on  a  number  of  the  other  cultivated  cruciferous  plants. 
On  wild  pepper  grass  and  shepherd's  purse,  the  stems  are  often 
considerably  distorted  by  its  presence. 

RASPBERRY,  Ruhus  sps. 

Anthracnose,  Gl(£osporium  Venetum  Speg.  Rarely  this 
forms  minute  white  spots  on  the  leaves,  but  on  the  stems  it 
occurs  very  commonly.  Here  it  produces  oval  to  circular  white 
spots,  often  merging  into  one  another,  with  purplish  borders. 
It  occurs  most  conspicuously  on  the  new  canes ;  on  the  old 
canes  which  carry  it  over  the  winter,  the  spots  often  become 
sunken  and  less  prominently  colored.  So  far  only  summer 
spores  have  been  found.  At  pruning  time  the  diseased  canes 
should  be  cut  out  as  thoroughly  as  possible;  and  after  the 
disease  has  started  on  the  new  canes  the  worst  of  these  might 
be  taken  out.  In  the  spring  before  the  buds  swell,  the  canes 
should  be  sprayed  with  Bordeaux  mixture;  if  repeated  after 
the  leaves  develop,  care  should  be  taken  to  get  it  on  the  young 
canes  chiefly.  [Reps.  1889,  p.  172;  1893,  p.  98;  1899,  P-  ^74; 
Bull.  142,  p.  16.] 

Cane  Blight,  Sphcsrella  ruhina  Pk.  Plate  XXIV,  e.  This 
blight  is  not  uncommon  and  causes  considerable  injury  in  the 
writer's  opinion.  Apparently,  it  is  most  troublesome  on  the  red 
varieties.  In  its  early  stage  the  trouble  might  be  mistaken  for 
a  bacterial  disease,  so  it  is  called  blight.  It  first  shows  on  the 
young  canes  early  in  July,  usually  at  the  lower  nodes  from 
which  the  leaves  have  fallen.     It  spreads  downward  from  the 


354        CONNECTICUT    EXPERIMENT   STATION    REPORT,    I903. 

base  of  the  leaf,  or  its  scar,  as  an  elongated  purple  blotch,  which 
shows  very  superficial  injury  to  the  bark.  Rarely  these  blotches 
start  away  from  the  node.  The  blotches  gradually  appear  at 
the  higher  nodes  and  slowly  grow  in  size,  sometimes  completely 
surrounding  the  stem.  In  the  fall  the  diseased  stems  turn 
whitish  all  over,  and  during  the  following  winter  the  asco-spore 
receptacles  appear  as  small  black  specks,  thickly  scattered  over 
this  whitened  bark.  The  spores  are  matured  by  May  and  ready 
for  the  infection  of  the  young  canes.  So  far  no  summer  spore 
stage  has  been  found.  The  foliage  of  the  infected  canes  is 
usually  streaked  with  yellow  and  crinkled.  The  treatment 
described  for  anthracnose  will  apply  here.     [Bull.  142,  p.  16.] 

Crown  Gall,  f  Dendrophagus  glohosus  Toum.  Plate 
XXIV,  d.  It  is  uncertain,  as  yet,  whether  this  is  exactly  the 
same  as  crown  gall  of  plum  or  not.  The  raspberry  often  has 
distinct  knots  very  similar  to  those  of  the  plum  and  peach,  but 
usually  they  extend  in  more  or  less  merged  excrescences  along 
the  stem  for  some  distance.  Care  should  be  used  not  to  get 
stock  from  a  plantation  containing  the  disease;  and  certainly 
no  plant  showing  it  should  be  set  out.  Affected  canes,  when 
discovered,  should  be  removed.  See  Plum.  [Bull.  142,  p.  16.] 
.  Leaf  Spot,  Septoria  Ruhi  West.  Common  on  leaves  ;  occurs 
on  wild  species,  as  Ruhiis  odoratus,  etc.     See  Blackberry. 

Orange  Rust,  Gymnoconia  inter stitialis  (Schl.)  Lagerh, 
Common  on  leaves  of  cultivated  and  wild  species.  See  Black- 
berry. 

Wilt,  Leptosphceria  Coniothyrium  (Fckl.)  Sacc.  The  sum- 
mer stage  {Coniothyrium  Fiickelii)  has  been  described  by 
Stewart,  of  New  York,  as  responsible  for  a  serious  cane  blight 
of  raspberries  in  that  state.  The  fungus  causes  dead  areas  in 
the  bark  and  wood,  sometimes  completely  girdling  the  bark,  so 
that  the  parts  above  wilt  and  finally  die.  The  fungus  is  some- 
times associated  with  the  blight  fungus  and  their  fruiting  pus- 
tules are  not  easily  distinguished,  except  when  the  former  have 
shed  out  the  spores  in  a  dusty  "brown  coating.  On  old  stems 
this  summer  spore  stage  is  often  associated  with  an  asco-spore 
stage  {Leptosphceria),  which  is  believed  to  be  merely  another 
stage  of  the  same  fungus.  Both  stages  have  been  found  here, 
but  as  yet  serious  injury  has  not  been  traced  directly  to  the 
parasitic  one.     There  has,  however,  been  called  to  the  writer's 


NOTES    ON    PARASITIC    FUNGI.  355 

attention  a  trouble  of  blackcaps  that  may  be  caused  by  it. 
The  fruiting  canes,  about  the  time  the  fruit  should  begin  to 
turn,  suffer  from  a  serious  wilt  that  dries  up  the  berries.  Spray- 
ing experiments  conducted  by  Stewart  gave  no  beneficial  results. 
Yellozvs.  Another  trouble  described  by  Stewart  is  the  yel- 
lows, which,  apparently,  is  not  uncommon  in  this  state.  The 
foliage  becomes  crinkled  and  mottled  with  yellowish  streaks, 
and  the  fruiting  canes  often  die  before  the  fruit  matures.  This 
seems  to  be  a  physiological  trouble,  possibly  similar  to  the  yel- 
lows of  peach.  Spraying,  with  Stewart,  gave  no  benefit.  The 
writer  has  found  it  worst  on  soil  poor  in  nitrogen. 

E>EB  BUD,  Cercis  Canadensis. 

Leaf  Spot_,  Cercospora  cercidicola  Ell.  This  is  not  uncom- 
mon in  nurseries.  The  leaves  develop  conspicuous  reddish 
brown  or  purplish,  circular  spots,  one-quarter  to  three-quarters 
of  an  inch  in  diameter. 

RED   TOP,  Agrostis  alba  var.  viilgaris. 

Black  Stem  Rust^  Puccinia  graminis  Pers.  Not  uncommon. 
See  Oats. 

Smut,  Ustilago  siricBfonnis  (West.)  Niessl.  The  smut  is 
found  most  commonly  from  May  to  July.  It  occurs  on  the 
leaves,  forming  dusty  outbreaks  of  the  spores  in  elongated 
lines.  These  often  involve  the  whole  blade,  and  the  plants 
are  more  or  less  stunted  in  their  growth.  After  the  spores 
fall  out,  the  foliage  becomes  more  or  less  shredded.  The  fun- 
gus also  occurs  here  on  timothy. 

RHUBARB,  Rheum  Rhaponticum. 

Leaf  Spot,  Ascochyta  Rhei  Ell.  &  Ev.  Pie-plant  leaves  not 
uncommonly  have  brownish  spots  of  varying  size  and  shape. 
Very  often  these  show  no  sign  of  the  fruiting  stage  of  a  fungus. 
In  some  cases,  however,  this  fungus  has  been  found. 

ROSE,  Rosa  sp. 

Leaf  Blotch,  Actinonema  Rosce  (Lib.)  Fr.  Plate  XXV,  c. 
Greenhouse  growers  report  this  trouble  more  serious  on  the 
hybrid  tea  roses.  La  France,  Liberty,  Meteor,  than  on  the  hybrid 


356        CONNECTICUT   EXPERIMENT   STATION    REPORT,    I903. 

perpetual.  One  or  several  purplish  spots  appear  on  the  leaf- 
lets. These  sometimes  attain  half  an  inch  in  diameter.  With 
a  lens,  the  mycelium  can  be  seen  radiating  out  from  the  center 
on  the  upper  surface  of  the  spots.  When  badly  infected,  the 
leaves  turn  yellowish  and  drop  off.  The'  disease  also  occurs 
on  the  hardy  outdoor  roses.  Some  of  the  greenhouse  men 
recommend  the  sulphur  and  oil  paint  on  the  heating  pipes  for 
this  trouble.  Spraying  with  potassium  sulphide  may  also  prove 
helpful.     [Rep.  1893,  p.  86;  Bull.  142,  p.  17.] 

Leaf  Spot,  Cercospora  rosicola  Pass.  This  is  not  nearly  so 
common  or  injurious  as  the  preceding.  The  spots  are  smaller, 
less  than  one-eighth  of  an  inch  usually,  and  often  have  a  lighter 
center  with  a  purplish  border. 

Powdery  Mildews,  SphcBrotheca  Humuli  (DC.)  Burr.,  S. 
pannosa  (Wallr.)  Lev.  Plate  XXV,  a.  The  former  mildew 
is  the  common  one  seen  in  greenhouses.  It  forms  a  scattered, 
mealy,  or  cobweb-like  growth  over  the  surface  of  the  leaves, 
causing  them  to  become  more  or  less  crinkled.  If  badly 
infected,  they  may  fall  off.  Only  the  conidial  stage  occurs.  Tea 
roses  are  most  likely  to  suffer ;  among  those  most  seriously 
affected  are  Saffrano,  Bon  Silene,  Bride,  Bridesmaid,  Niphetos, 
Pierpont  Morgan,  Goldengate.  Greenhouse  men  try  to  avoid 
drafts  and  use  care  in  watering  to  keep  down  this  trouble. 
Sulphur  is  very  commonly  sprinkled  on  the  leaves,  and  when 
the  fires  are  started,  sulphur  and  oil  mixture  is  painted  on  the 
pipes.  The  second  mildew  given  above  has  been  collected  but 
once,  on  an  outdoor  rambler  rose.  A  thick  felt  of  whitish 
mycelium  develops  on  the  branches  and  more  sparingly  on  the 
leaves.     The  winter  stage  occurs  imbedded  in  this.     [Bull.  142, 

p.  17.] 

Rust,  Phragmidium  suhcorticium  (Schrank)  Wint.  All 
three  stages  occur  on  this  host,  most  frequently  on  the  leaves. 
Sturgis  notes  injury  to  cultivated  plants.     [Report  1893,  p.  86.] 

RTJTA-BAGrA,  Brassica  campestris. 

Powdery  Mildew,  Erysiphe  Polygoni  DC.  Conidial  stage 
only.     See  Turnip. 

RYE,  Secale  cereale. 

Black  Stem  Rust,  Puccinia  graminis  Pers.  Common  on  the 
stems.     See  Oats. 


NOTES   ON    PARASITIC    FUNGI.  35/ 

Ergot,  Claviceps  purpurea  Tul.  Plate  XXV,  b.  This  is 
commonly  found  in  volunteer  rye.  The  conspicuous  sclerotia, 
or  compacted  masses  of  sterile  mycelium,  show  as  purplish  horns 
extending  fronT  the  floral  parts  of  the  spike.  It  is  from  these, 
after  they  have  fallen  to  the  ground  and  become  buried,  that 
the  asco-spore  stage  develops  the  next  year.  Ergot  is  poisonous, 
and  where  abundant  in  grain,  if  eaten  by  cattle,  may  cause 
serious  trouble.  A  number  of  other  grasses  have  smaller 
sclerotia  developing  in  their  flower  parts,  probably,  in  most 
cases,  a  species  different  from  this. 

Orange  Leaf  Rust,  Puccinia  ruhigo-vera  (DC.)  Wint.  This 
is  common  on  the  leaves,  forming  spore  pustules  similar  to  those 
of  the  crown  rust  of  oats,  though  the  spores  are  very  different. 
[Rep.  1890,  p.  98.] 

Smut,  Urocystis  occulta  (Wallr.)  Rabh.  Thaxter  reported 
this  smut  not  uncommon,  but  not  very  injurious.  The  writer 
has  found  it  once  in  very  limited  quantity.  The  black,  dusty 
spore  masses  break  out  in  lines,  rather  completely  covering  the 
inner  surface  of  the  leaf  sheaths. 

SALSIFY,  Tragopogon  porrifolius. 

Powdery  Mildew,  ?  Erysiphe  cichoracearum  DC.  Occa- 
sionally this  forms  an  inconspicuous  growth  of  the  conidial 
stage  on  the  leaves. 

White  Rust,  Albugo  Tragopogonis  (Pers.)  Gray.  In  one 
market  garden  near  New  Haven  this  was  found  doing  some 
damage.  The  summer  spores  occur  as  white  blisters  on  the 
leaves  and  on  the  rupture  of  the  covering  epidermis  become 
scattered. 

SNAPDRAGON",  Antirrhinum  ma  jus. 

Anthracnose,  Colletotrichum  Antirrhini  Stew.  In  one 
instance  this  was  found  seriously  injuring  Snapdragons  grown 
outdoors.  The  leaves  and  stems  become  rather  abundantly 
covered  with  whitish  spots,  usually  oval  in  shape  and  marked 
with  a  distinct  purple  border.  Generally  these  are  about  one- 
fourth  of  an  inch  in  diameter,  but  by  merging,  may  form  an 
extended  area.  Very  small  black  dots  in  the  center  show  the 
fruiting  stage  of  this  imperfect  fungus.  In  the  fall,  all  of  the 
parts  above  ground  should  be  cut  off  and  the  rubbish  burned. 


358        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

SOAPWORT,  Saponaria  officinalis. 

Leaf  Mold,  Macrosporium  Saponarice  Pk.  The  fungus 
causes  whitish  or  greyish  leaf  spots,  a  quarter  of  an  inch  or  less 
in  diameter.  The  fungus  probably .  belongs  under  Alternaria 
rather  than  under  Macrosporium. 

SORGrHUM,  Sorghum  vulgare. 

Grain  Smut,  Sphacelotheca  Sorghi  (Lk.)  Clint.  Usually 
each  grain  of  the  entire  panicle  is  changed  into  a  slightly  elon- 
gated smutted  body.  The  same  smut  occurs  on  broom  corn, 
but  neither  of  these  hosts  are  grown  commercially  in  this  state. 
The  trouble  can  be  prevented  by  either  the  hot  water  or  formalin 
treatment  of  the  seed. 

Red  Spot,  Colletotrichum  lineola  Cda.  The  leaves  become 
streaked  with  elongated  bright  red  spots  which  run  together. 
The  fruiting  stage  shows  on  these  as  black  pustules. 

SPINACH,  Spinacia  oleracea. 

Anthracnose,  Colletotrichum  SpinacicB  Ell.  &  Hals.  Pos- 
sibly this  may  occur  more  abundantly,  but  so  far  only  a  few 
specimens  have  been  found.  It  forms  greyish  elliptical  to  cir- 
cular spots,  a  quarter  of  an  inch  in  diameter,  on  the  leaves. 

SPIR.ffiA,  Spircea  Ulmaricz. 

Leaf  Spot,  Septoria  Ulmarioe  Oud.  Rather  injurious  to  the 
foliage. 

SQUASH,  Cucurhita  sps. 

Anthracnose,  Colletotrichum  Lagenarium  (Pass.)  Ell.  & 
Hals.  On  ripe  or  stored  squashes  this  is  not  uncommon, 
and,  possibly,  it  may  also  cause  injury  earlier  in  the  season. 
The  depressed,  rotten  areas  may  attain  considerable  size,  and 
usually  show  the  pinkish  fruiting  pustules.  The  fungus  often 
opens  the  way  for  a  general  rot  by  other  fungi  and  bacteria. 
See  Watermelon. 

Black  Mold,  Rhisopus  nigricans  Ehr.  Plate  XXVI,  b. 
This  is  a  common  mold  on  rotting  fruit  and  vegetables.  It 
occurs,  sometimes  with  the  next  fungus,  on  the  fading  flowers 
of  the  summer  squash,  and  in  some  cases  is  responsible  for  a 
rot  of  the  fruit.     See  Sweet  Potato. 


NOTES    ON    PARASITIC    FUNGI.  359 

Metallic  Mold,  Choanephora  cucurbitarum  (B.  &  R.) 
Thaxt.  Plate  XXVI,  c.  Very  often  the  black  mold  described 
above  occurs  with  this  on  the  faded  flowers,  but  the  former 
can  be  told  with  a  lens  by  its  shorter  threads,  bearing  firmer, 
spherical  spore  heads.  This  latter  fungus  is  also  easily  dis- 
tinguished by  the  metallic  luster  of  the  threads  and  the  more 
loosely  compacted  heads.  It,  no  doubt,  often  blasts  the  blossoms 
and  may  rot  the  young  fruit  also. 

Powdery  Mildew,  Erysiphe  cichoracearum  DC.  Conidia 
only.     See  Pumpkin. 

Wilt,  Bacillus  tracheiphilus  Sm.  Plate  XXVI,  a.  In  this 
disease,  bacteria  clog  the  ducts  of  the  stem  or  leaf  petioles,  so 
that  the  water  supply  is  largely  cut  off  from  the  parts  beyond,  and 
these  wilt  and  eventually  die.  Cutting  across  the  stems,  one  can 
often  squeeze  out  these  organisms  in  a  slight,  viscid,  milky 
exudation.  Apparently,  insects  distribute  these  germs  and  per- 
haps produce  the  disease  through  punctures  in  the  leaves  or  by 
eating  holes  in  them.  Very  often,  diseased  leaves  are  found 
where  the  trouble  has  run  down  the  petiole  and  in  some  cases 
extended  into  the  stem.  The  tissues  of  the  leaf  are  more  likely 
to  show  a  diseased  condition  than  are  the  vascular  bundles 
in  the  stem.  Spraying  does  not  seem  to  lessen  this  trouble. 
The  wilted  vines  should  be  removed  and  care  taken  to  keep 
down  the  insects.  Summer  and  Hubbard  squash,  also  musk 
melons  and  cucumbers,  are  subjected  to  this  wilt,  which  last 
year  was  more  common  than  usual. 

STKAWBERRY,  Fragaria  sps. 

Fruit  Rot,  Botrytis  vulgaris  Fr.  When  the  writer  first 
came  to  the  Station  in  July,  1902,  he  found  some  strawberries 
that  had  recently  been  sent  in  for  examination,  because  they 
were  rotting  badly  on  the  vines.  The  common  grey  mold 
was  abundant  on  these  and  has  since  been  seen  occasionally  in 
the  field.  Last  year  some  growers  complained  of  a  rot  trouble 
of  the  ripening  fruit,  which  was  probably  caused  by  this  fungus. 
Apparently,  the  crop  often  suffers  during  wet  weather  at  harvest 
time  from  this  rot.     When  it  is  likely  to  prove  serious,  the 


24 


360        CONNECTICUX.  EXPERIMENT   STATION    REPORT,    I903. 

writer  should  judge  that  it  could  be  minimized  by  carefully 
gathering  the  rotten  fruit  at  each  picking. 

Leaf  Blotch,  Ascochyta  Fragarice  Sacc.  This  is  not  so  com- 
n:on,  and  consequently  not  so  injurious  as  the  next  trouble, 
though  occasionally  it  is  found  doing  considerable  damage. 
The  two  are  very  similar  in  appearance,  but  with  this  one  the 
purplish  blotches  are  larger,  often  merged,  producing  a  general 
browning  of  the  margins  of  the  leaves. 

Leaf  Spot,  Sphczrella  Fragarice  (Tul.)  Sacc.  Plate  XXV,  d. 
The  spots  on  the  leaflets  are  usually  distinct,  circular,  and 
possess  a  prominent  purple  border  and  a  whitish  center.  The 
imperfect  or  summer  stage  is  parasitic,  while  the  winter  or  asco- 
spore  stage  develops  on  the  old  dead  leaves.  The  destruction 
of  these  leaves  is  therefore  helpful  in  keeping  the  trouble  in 
check.  Some  growers  mulch  the  beds  with  salt  hay  and  then 
burn  them  over  in  the  spring,  thus  destroying  the  old  leaves. 
Others  advocate  the  very  frequent  renewal  of  the  beds,  as  the 
trouble  becomes  worst  in  old  beds.  Spraying  with  Bordeaux 
has  also  been  found  useful.  One  treatment  is  given  before 
blossoming,  another  after  most  of  the  petals  fall,  and  a  third 
and  perhaps  fourth  after  the  picking  season. 

Frosty  Spots.  Last  fall  some  of  the  growers  near  New 
Haven  complained  of  a  new  leaf  trouble  that  resembled  mildew. 
An  examination  of  the  leaves,  however,  showed  that  the  whitish 
spots  were  not  due  to  any  fungus  but  resulted  from  the  flak- 
ing away  of  the  cuticle.  Later,  the  whitish  appearance  gave 
place  to  dead  brown-  spots.  Evidently,  the  trouble  was  a 
physiological  one  that  had  resulted  in  the  flaking  up  of  the 
cuticle  and  the  collapse  of  the  epidermal  cells.  This  was, 
apparently,  not  due  to  frost,  since  it  appeared  chiefly  before 
the  first  frosts.  It  was  worst  on  plants  set  out  between  rows 
of  early  potatoes,  and  probably  this  treatment,  with  the  unusually 
moist  season,  prevented  the  proper  transpiration  of  water,  which 
produced  the  injury  through  rupture  of  the  cells. 

SUNFLOWER,  Helianthus  annuus. 

Leaf  Spot,  Septoria  Helianthi  Ell.  &  Kell.  Produces  sub- 
circular  or  irregular  brownish  spots  from  which  the  tissue 
sometimes  drops  out. 


NOTES    ON    PARASITIC    FUNGI.  361 

RusT_,  Puccinia  Helianthi  Schw.  The  uredo-  and  teleuto- 
spores  break  out  on  either  side  of  the  leaves^  but  more  abun- 
dantly below,  in  numerous  reddish  dusty  pustules,  about  the 
size  of  a  pencil  point. 

SWEET  POTATO,  Ipomoea  Batatas. 

Black  Mold^  Rhisopiis  nigricans  Ehrb-  This  produces  a 
soft  rot  of  the  roots.  The  grocer  and  the  housewife  very  often 
find  it  difficult  to  keep  potatoes  because  of  its  attacks.  Where 
the  skin  is  broken,  the  fungus  develops  its  fruiting  stage  as 
a  dense  growth  of  blackish  threads,  ending  in  the  small  spore 
capsules. 

SWEET    VERNAL    GRASS,  Anthoxanthum  odoratum. 

Smut^  Tilletia  Anthoxanthi  Blytt.  This  changes  the  seed 
into  an  inconspicuous  smutted  body.  The  smutted  spikes  are 
about  like  the  healthy  in  appearance,  so  the  fungus  is  easily 
overlooked.  The  only  time  it  has  been  collected  in  the  United 
States  was  by  the  writer  near  New  Haven  in  July,  1902. 

SYCAMORE,  Platanus  occidentalis. 

Anthracnose,  Gla;osporium  nervisequum  (Fckl.)  Sacc. 
The  leaves  with  this  trouble  develop  brown,  dead  areas  of 
varying  shape  and  size,  6ften  running  along  the  ribs.  The 
disease  may  become  so  serious  that  defoliation  takes  place. 
The  young  branches,  also,  are  said  to  be  attacked.  It  is  one  of 
the  worst  troubles  of  the  sycamore  in  this  state. 

TEOSINTE,  Euchlcena  luxurians. 
Smut,  Ustilago  Ze<2  (Beckm.)  Ung.     See  Corn. 

TIMOTHY,  Phleum  pratense. 

Ergot,  Claviceps  sp.  Small  slender  sclerotia  are  occasionally 
found  in  the  spikes. 

Smut,  Ustilago  striceformis  (West.)  Niessl.  On  leaves. 
See  Red  Top. 


362        CONNECTICUT    EXPERIMENT   STATION    REPORT,    I903. 

TOADFLAX,  Linaria  vulgaris. 

White  Smut,  Entyloma  Linarice  Schrt.  The  fungus  pro- 
duces small,  whitish,  circular  areas  on  the  leaves  and  stem  in 
which  the  spores  are  permanently  embedded. 

TOBACCO,  Nicotiana  Tabacum. 

Frost  Fungus,  Botryosporium  pulchruni  Cda.  (Bofrytis  lon- 
gibrachiaia) .  According  to  Sturgis,  this  fungus  sometimes  pro- 
duces a  stem  rot  in  the  tobacco  while  hanging  in  the  barns 
during  the  later  stages  of  curing.  He  says :  "Stems  affected 
with  this  disease  are  covered  with  pure  white  patches  having 
the  appearance  of  a  long  pile  velvet.  These  patches  spread 
rapidly,  encroaching  upon  the  veins  of  the  leaf  and  destroying 
the  tissue  and  in  the  end  inducing  a  more  or  less  widespread 
decay,  especially  in  the  neighborhood  of  the  midrib  and  veins. 
It  is  not  unusual  upon  entering  a  barn,  even  during  the  process 
of  curing,  to  find  the  floor  partially  covered  with  the  refuse  of 
the  previous  year's  crop,  the  latter  often  looking  as  though  a 
fall  of  snow  had  whitened  it,  so  densely  is  it  covered  with  the 
mycelium  and  spores  of  this  fungus.  The  slightest  current  of 
air  serves  to  separate  the  spores  from  their  attachment  and 
carry  them  through  the  barn,  some  finding  lodgment  upon  and 
at  once  infecting  the  curing  stems  and  leaves."  This  fungus  is 
common  in  greenhouses  upon  decaying  stems,  especially  tobacco 
stems,  left  on  the  moist  earth.  Under  certain  conditions  it  may 
act  as  a  parasite.  See  Vinca.  [Reps.  1891,  p.  184;  1893, 
p.  84.] 

Seed  Bed  Rot  {Fungus).  The  young  tobacco  plants  some- 
times dampen  off  in  the  seed  bed  apparently  through  the  action 
of  some  fungus.  This  trouble  has  not  been  thoroughly  studied 
yet.  Care  in  the  kind  of  soil  used  and  in  the  regulation  of 
temperature  and  moisture  in  the  beds,  should  help  to  check  a 
trouble  of  this  kind. 

Pole  Burn  {Fungi  and  Bacteria) .  Sturgis  also  made  a  special 
study  of  this  trouble,  which  sometimes  seriously  affects  tobacco 
while  drying  in  the  barns,  especially  when  the  weather  is  moist 
and  warm  and  the  barns  can  not  be  ventilated  properly.  He 
says  of  it:   "At  first  the  disease  is  limited  to  the  neighborhood 


NOTES    ON    PARASITIC    FUNGI,  363 

of  the  veins  and  midrib  of  the  leaf  where  moisture  is  super- 
abundant, but  its  spread  is  very  rapid,  the  small  blackened  areas 
increase  in  size,  become  confluent  and  sometimes  within  thirty- 
six,  or  at  most  forty-eight  hours,  not  only  is  the  whole  leaf 
affected  but  the  entire  contents  of  the  curing  barn  may  be 
rendered  quite  worthless  as  tobacco.  Examination  shows  that 
the  leaves  have  changed  from  greenish  yellow  to  a  dark  brown 
or  almost  black  color,  that  the  fine  texture  has  disappeared,  and 
that  instead  of  being  tough  and  elastic,  the  whole  leaf  is  wet 
and  soggy,  and  tears  almost  with  a  touch,  falling  of  its  own 
weight  from  the  stalk."  Sturgis  found  this  rotting  was  due 
to  various  bacteria  and  fungi.  Regarding  prevention,  he  states : 
"We  have  seen  that  whatever  is  the  primary  cause  of  pole  burn, 
its  ill  effects  can  be  in  a  large  measure,  if  not  entirely,  prevented 
by  a  proper  regulation  of  moisture  and  temperature."  [Reps. 
1891,  p.  168;    1899,  p.  265.] 

Calico  or  Mosaic  Disease.  This  is  a  trouble  met  in  the  grow- 
ing fields  of  tobacco.  The  affected  plants  are  ususLlly  somewhat 
stunted  in  growth,  and  the  leaves  have  a  pale  greenish  or  later 
a  peculiar  yellow  mottling,  due  to  changes  in  the  chlorophyll 
of  the  tissues.  Usually  these  yellow  streaks  or  areas  follow  the 
bundles  and  are  separated  by  the  normal  green  tissue.  The 
trouble  eventually  renders  the  plants  of  little  commercial  value. 
Most  growers  pull  up  the  diseased  plants  as  they  find  them  in 
the  field,  for  their  presence  in  the  cured  crop  would  only 
detract  from  its  value.  The  trouble  is  considered  a  physio- 
logical one,  rather  than  due  to  fungi  or  bacteria,  and  in  nature 
approaches  the  yellows  of  peach.  Certain  unfavorable  condi- 
tions in  setting  the  plants  or  of  the  soil  or  moisture  conditions 
are  said  to  produce  the  trouble.  As  yet,  however,  too  little  is 
known  of  all  the  circumstances  that  contribute  to  this  trouble 
and  how  to  avoid  it.     [Reps.  1898,  p.  242;    1899,  p..  252.] 

Rust.  The  cause  of  the  irregular,  usually  small,  spots  appear- 
ing on  the  leaves  in  the  field  and  called  "rust"  by  the  growers, 
is  not  known.  Possibly  it  is  also  a  physiological  trouble. 
[Rep.  1899,  p.  255.] 

Spot.  The  writer  has  found  in  tobacco  grown  under  cloth, 
circular,  brown  spots,  about  one-quarter  of  an  inch  in  diameter, 
on  the  leaves.     These  were  not  uncommon  in  one  field  and  had 


364        CONNECTICUT    EXPERIMENT   STATION    REPORT^    1903- 

the  appearance  of  the  spot  produced  by  the  Alternaria  fungus 
on  potato,  etc.  They  showed  the  usual  faint  concentric  rings 
of  development,  but  no  signs  of  any  fungus  were  discovered. 
This  is  probably  the  same  thing  described  by  Sturgis,  Rep.  1898, 
p.  254,  on  tobacco  grown  in  the  open.  He  assigned  no  cause. 
Its  presence,  in  moderate  amount,  is  not  generally  regarded 
as  a  damage  to  the  crop. 


TOMATO,  Lycopersiciim  esculentum. 

Anthracnose,  Colletotrichum  phomoides  (Sacc.)  Chest. 
Plate  XXVIII,  b.  This  was  found  in  a  few  fields  on  the  ripen- 
ing fruit,  producing  conspicuous  sunken  areas,  in  the  center  of 
which  numerous  closely  clustered  spore  pustules  occurred.  Evi- 
dently it  is  a  trouble  that  some  seasons  may  produce  serious 
injury  at  the  ripening  period. 

Blight^  Bacillus  Solanacearum  Sm.  Plate  XXVII,  a-c. 
The  southern  tomato  blight  was  found,  apparently  for  the  first 
time,  in  the  vicinity  of  New  Haven  last  season.  While  noticed 
in  several  fields,  it  was  only  in  the  field  of  Mr.  Andrew  Ure, 
described  here,  that  it  was  found  especially  injurious.  A  gen- 
eral view  of  the  affected  part  of  this  field  is  shown  in  Plate 
XXVII.  It  was  peculiar  in  that  four  rows  straight  through 
the  field  were  very  badly  infected,  many  of  the  plants  dying; 
the  bordering  rows  were  less  seriously  affected,  while  the 
remainder  of  the  field  away  from  these  was  practically  free 
from  the  disease.  So  far  as  could  be  learned,  there  was  no 
difference  in  the  field  or  the  treatment  that  could  have  produced 
this.  The  only  way  the  writer  could  explain  it  was  that  pos- 
sibly a  certain  block  of  the  plants  in*  one  of  the  seed  beds  had 
contracted  the  disease  and  had  been  set  out  together  in  the 
field.  Many  of  the  plants  had  been  killed  before  they  showed 
any  considerable  growth  in  the  field.  Others  less  seriously 
infected  were  somewhat  smaller  than  the  healthy  plants  and 
showed  diseased  leaves  here  and  there.  The  leaves  on  any 
part  of  the  plant  were  affected,  sometimes  first  turning  yellow, 
but  usually  soon  dying  outright.  Very  often  the  leaflets  and 
most  of  the  petiole  were  brown  and  dead,  while  the  lower  part 
of  the  petiole  for  an  inch  or  two  was  still  alive  and  green.     Cut- 


NOTES    ON    PARASITIC    FUNGI.  365 

ting  across  the  green  stems  or  petioles,  the  trouble  showed  as 
diseased  brownish  spots,  or  as  a  complete  ring  in  the  bundles, 
which  are  situated  between  the  pith  and  the  bark.  In  severe 
cases  there  was  also  a  lesion  of  the  tissues  in  this  vicinity.  See 
Plate  XXVII,  c.  In  very  advanced  stages  the  base  of  the  stems 
showed  a  general  soft  rot.  Sometimes  the  leaves  showed  dead 
areas  around  the  bundles  and  examination  of  the  ducts  showed 
these  choked  with  bacteria.  It  was  not  determined  if  this  was 
caused  by  the  same  bacterial  agents  that  produced  disease  in  the 
potatoes  this  same  year  ;  there  is  a  possibility  that  it  was.  The 
potato  bug  and  other  insects  probably  carry  this  disease  after 
it  gets  started  in  a  field.  It  should  be  noted  in  this  case, 
however,  that  the  disease,  apparently,  did  not  spread  through 
the  field,  neither  were  the  potato  bugs,  etc.,  numerous  last  year. 
Downy  Mildew,  Phytophthora  infesfans  DeBy.  Thaxter 
collected  this  fungus  on  the  tomato  where  it  was  doing  damage ; 
but  apparently,  its  occurrence  on  this  host  is  comparatively  rare. 
See  Potato.     [Reps.  1890,  p.  95  ;    1893,  p.  103.] 

Fruit  Mold,  Macrosporium  Tomato  Cke.  Very  commonly, 
this  forms  a  dense,  olive-black,  moldy  growth  on  the  point  rot 
of  the  fruit  and  formerly  was  thought  to  be  the  cause  of  this 
trouble,  but  now  it  is  considered  only  a  saprophyte.  See  Point 
Rot. 

Leaf  Mold,  AUernaria  Solani  (E.  &  M.)  J.  &  G.  Occurs  not 
uncommonly  on  the  leaves,  occasionally  doing  damage.  Often 
it  is  associated  with  the  next  trouble  and  may  be  mistaken  for 
it.     See  Early  Blight  of  Potato. 

Leaf  Spot,  Septoria  Lycopersici  Speg.  This  is  one  of  the 
most  serious  troubles  of  the  tomato  and  has  come  into  promi- 
nence during  recent  years.  The  leaves,  stem  and,  rarely,  the 
green  fruit,  may  be  attacked.  The  trouble  is  most  injurious 
to  the  leaves,  which  become  thickly  covered  with  small,  angular 
spots,  usually  having  a  greyish  center  and  a  deeper  colored 
border.  Apparently,  it  rarely  matures  on  the  small  black  specks 
it  may  produce  on  the  fruit.  Very  probably  it  passes  the 
winter  through  the  summer  spores  formed  in  the  fruiting 
receptacles  on  the  stems,  since  no  winter  spore  stage  has  been 
associated  as  yet  with  it.  The  trouble  may  be  prevented  largely 
by  spraying  with  Bordeaux.  The  first  spraying  should  be 
given  a  couple  of  weeks  after  transplanting,  and  two  or  three 


366        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I903. 

additional  sprayings  should  follow  each  other  at  intervals  of 
about  three  weeks.     [Bull.  142,  p.  18.] 

Scab,  Cladosporium  fulvum  Cke.  This  fungus  forms  dense 
olive-brown  growths  in  areas  of  varying  size,  on  the  under 
surface  of  the  leaves,  and  often  produces  discoloration  of  the 
tissues  on  the  upper  surface.  It  is  a  trouble  that  occurs  both 
in  the  field  and  greenhouse  and  sometimes  does  considerable 
injury.  Spraying  with  Bordeaux,  if  taken  in  time,  will  pre- 
vent it.  In  the  greenhouse  care  should  be  used  in  sprinkling 
water  on  the  foliage,  and  the  vines  should  not  be  planted  too 
closely.  [Reps.  1889,  p.  173  ;  1890,  p.  95  ;  1893,  p.  102  ;  Bulls. 
Ill,  p.  15;   115,  p.  16.] 

Sleeping  Disease  or  Wilt,  Fusarium  Lycopersici  Sacc.     In 
the  Experiment  Station  greenhouse,  for  several  years  past,  this 
trouble  has   appeared  with  increasing  severity.     As   the  seed 
has  been  selected  each  year  from  these  plants,  possibly  this 
explains  in  part  the  severity  of  the  trouble.     It  does  not  usually 
show  until  the  plants  have  attained  full  size  and  are  beginning 
to  blossom  abundantly.     At  first,  a  lower  leaf  or  two  will  wilt, 
turn  yellow  and  finally  die.     Gradually,  the  disease  works  up, 
successive  leaves   dying  and  drying  up  on  the  vine.     At  the 
time  the  plants  come  into  bearing,  the  trouble  usually  shows 
prominently.     Cutting  across  the  green  stem  or  petioles  at  the 
base  of  the  plant,  the  disease  first  shows  a  discoloration  in  the 
vicinity  of  the  bundles.     Very  often  three  diseased  spots  show 
in  these  cross  sections.     If  the  fibro-vascular  bundles  are  exam- 
ined  in  cross  section  under  the  microscope,  they  are  found  to 
be  more  or  less  filled  with  the  mycelium  of  the  fungus.     This 
choking  up  of  the  vessels,  with  their  later  diseased  condition, 
prevents  the  proper  amount  of  moisture  being  carried  up  the 
plants,  which  in  time  suffer  severely  because  of  this.     As  the 
leaves  die,  the  fungus  may  work  to  the  surface  from  the  vicinity 
of  the  petiole,  producing  dead  areas  on  the  stem  which  eventu- 
ally show  abundance  of  the  whitish  mycelium.     The  spores  are 
formed   abundantly  on   this,   and   it   then   assumes   a  pinkish 
color  from  their  presence.     Eventually,  the  whole  plant  dies 
and  dries  up,  the  stem  becoming  more  or  less  completely  cov- 
ered with  the  pinkish,  moldy  growth.     Very  often  this  pink 
mold  may  show  on  the  ripe  fruit,  especially  at  the  base,  develop- 


NOTES    ON    PARASITIC    FUNGI.  367 

ing  out  on  it  from  the  petiole.  The  disease  is  unquestionably 
carried  in  the  soil  and  possibly  also  by  the  mycelium  develop- 
ing up  the  petioles  into  the  seed.  In  cutting  across  green 
fruit,  one  occasionally  finds  that  the  disease  has  penetrated 
partially  into  it,  and  in  this  way  may  finally  reach  up  into  the 
seed.  Where  the  trouble  is  established  in  a  greenhouse,  sterili- 
zation of  the  soil  and  treatment  of  the  seed  with  hot  water  will 
apparently  stop  the  trouble,  if  done  thoroughly.  Perhaps  it 
would  be  best  merely  to  sterilize  the  soil  and  get  seed  from 
an  uninfected  source. 

Point  Rot.  Plate  XXA/"!!!,  a.  Apparently,  the  point  rots  of 
the  greenhouse  and  the  field  are  the  same  trouble.  It  usually 
first  shows  on  the  green  fruit  as  a  sunken,  brown,  rotted  spot 
at  the  blossom  end.  This  gradually  enlarges,  and  later  often 
becomes  more  or  less  covered  with  mold,  especially  the  black 
mold.  As  yet,  the  cause  of  point  rot  is  not  surely  known — it 
may  be  a.  bacterial  trouble  or  it  may  be  a  physiological  one. 
Selby,  of  Ohio,  states  that  sub-irrigation  in  the-  greenhouse 
will  largely  prevent  it.  Spraying  has  not  given  very  encour- 
aging results. 

TULIP    TREE,  Liriodendron  Tulipifera. 

Powdery  Mildew,  Erysiphe  Liriodendri  Schw.  Forms  a 
rather  inconspicuous  cobweb-like  growth  on  the  leaves.  The 
asco-spore  stage  is  not  produced  very  abundantly. 

TURNIP,  Brassica  sps. 

Club  Root,  Plasmodiophora  Brassicce  Wor.     See  Cabbage. 

Downy  Mildew,  Peronospora  parasitica  (Pers.)  Tul.  Plate 
XXVIII,  c.  The  fungus  forms  whitish  tufts  of  the  summer 
spore  stage  in  patches  on  the  lower  surface  of  the  leaves  and 
produces  discoloration  of  the  tissues  above.  It  occurs  rather 
commonly  in  the  fall  in  turnip  (Brassica  Rapa)  fields  and  has 
also  been  found  on  the  radish. 

Powdery  Mildew,  Erysiphe  Polygoni  DC.  The  conidial 
stage  only  occurs  on  the  upper  surface  of  the  leaves  (Brassica 
campestris) ,  producing  the  usual  whitish  powdery  growth. 


368        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

Scab,  Oospora  scabies  Thaxt.  Observed  by  Sturgis  on 
roots  of  both  Brassica  campestris  and  B.  Rapa.  See  Potato. 
[Reps.  1894,  p.  126;   1896,  p.  266.] 


VINCA,  Vinca  7iiajor. 

Frost  Fungus,  Botryosporinm  pulchruin  Cda.  Ordinarily 
this  fungus  occurs  as  a  saprophyte  on  dead  stems  lying  on  the 
moist  ground,  but  on  the  Vinca  it  acted  as  a  parasite.  However, 
the  varigated  vinca  plants  were  in  pots  placed  temporarily  under 
the  greenhouse  benches,  where  the  water  dropped  down  from 
above,  so  the  conditions  were  favorable  for  the  fungus,  but 
not  for  the  plants.  The  plants  became  so  abundantly  infested 
with  the  fungus  that  they  were  all  killed.  The  luxuriant,  white 
growth  resembles  somewhat  the  very  heavy  hoar  frost  that 
sometimes  covers  sticks  on  the  ground.  Examining  it  carefully 
with  a  hand  lens,  the  erect  threads,  about  one-quarter  of  an  inch 
high,  are  seen  to  be  provided  with  diverging  side  branches  upon 
which  are  clustered  the  spores,  the  whole  having  a  feathery 
aspect.     See  Tobacco. 


VIOLET,  Viola  odorata. 

Anthracnose,  CoUetotrichum  ViolcB-tricoloris  Sm.  Occurs 
occasionally  on  the  leaves. 

Leaf  Blight,  Cercospora  Violce  Sacc.  Apparently  occurs 
only  occasionally,  the  spot  disease  being  the  common  trouble. 

Leaf  Spot,  Phyllosticta  Violce  Desm.  Another  occasional 
trouble.  [Rep.  1891,  p.  166.]  These  three  leaf  fungi  are  very 
similar  in  appearance,  producing  whitish  or  greyish  spots. 

Root  Rot,  Thielavia  basicola  Zopf.  Reported  by  Thaxter  in 
Rep.  1 89 1,  p.  166. 

Spot  Disease, /^/^^rnana  Violce  Gall.  &  Dor.  Plate XXVIII,  d. 
This  seems  to  be  the  chief  trouble  with  greenhouse  violets  in 
this  state.  The  white  spots  are  circular,  usually  about  one- 
eighth  of  an  inch  in  diameter.  They  seem  to  start  as  black 
specks ;  and  on  the  stem  this  blackening  is  most  pronounced. 
It  is  only  rarely  that  the  writer  has  found  the  Alternaria  pro- 
ducing spores  on  these  spots,  which  seems  strange  since  the 
disease  often  spreads  rapidly  in  the  beds.     The  trouble  is  likely 


NOTES    ON    PARASITIC    FUNGI.  369 

to  get  started  in  the  houses  in  the  fall  before  heat  is  turned 
on,  especially  if  the  grower  is  trying  to  cut  down  his  coal  bill. 
The  character  of  the  house,  as  to  moisture,  soil,  etc.,  probably 
also  plays  a  prominent  part  in  the  trouble.  The  disease  is 
very  often  worst  where  violets  have  been  grown  for  some  time. 
Growers  generally  pick  off  the,  diseased  leaves  as  soon  as  they 
appear;  in  bad  cases,  however,  this  often  means  very  severe 
pruning.  Possibly  the  thorough  removal  of  all  diseased  leaves 
when  the  plants  are  set  out,  followed  with  a  treatment  with 
Bordeaux  mixture,  might  prove  helpful  in  preventing  the  trouble. 
After  the  disease  is  thoroughly  started,  perhaps  little  can  be 
expected  from  spraying.     [Bull.  142,  p.  18.] 

VIRGINIA    CREEPER,  Ampelopsis  quinquefolia. 

Leaf  Spot,  Phyllosticta  Labruscce  Thm.  On  the  leaves  only. 
See  Grape. 

Powdery  Mildew,  Uncinula  necator  (Schw.)  Burr.  See 
Grape. 

WALNUT,  Juglans  nigra. 

Anthracnose,  Marsonia  Juglandis  (Lib.)  Sacc.  Produces 
subcircular,  usually  dark  reddish  brown,  spots  or  blotches  on  the 
leaves. 

WATERCRESS,  Nasturtium  officinale. 

Leaf  Spot,  Cercospora  Nasturtii  Pass,  Produces  roundish 
light  colored  spots  on  the  foliage,  thus  rendering  it  inferior  for 
decorative  purposes. 

WATERMELON,  Citrulhis  vulgaris. 

Anthracnose,  Collet otrichum  Lagenarium  (Pass.)  Ell.  & 
Hals.  Plate  XXVIII,  e.  This  fungus  occurs  on  both  the  fruit 
and  the  leaves.  On  the  former  it  produces  sunken,  rotted  areas, 
at  first  small,  but  increasing  in  size  and  number,  usually  until 
the  melon  is  worthless.  On  these  areas,  the  spores  ooze  out  in 
viscid,  pinkish  masses ;  sometimes  they  may  germinate  in  posi- 
tion, giving  rise  to  a  superficial  growth  of  white  mycelium,  as 


370        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I903. 

shown  in  the  plate.  Either  green  or  ripe  fruit  may  be  attacked. 
On  the  leaves,  the  fungus  causes  dead  brown  areas,  upon  which 
the  exudation  of  spores  may  not  be  very  conspicuous.  This 
same  fungus  occurs  on  cucumbers,  musk  melons  and  squash. 
In  the  fall,  the  old  vines  and  rotted  fruit  should  be  gathered 
from  the  field  and  burned,  as  they  help  to  carry  the  trouble  in 
the  soil.  Spraying  with  Bordeaux  should  begin  when  the  vines 
start  to  run,  and  these  should  be  kept  covered  during  the  season. 
[Bull.  142,  p.  7.] 

Downy  Mildew,  Plasmopara  Cuhensis  (B.  &  C.)  Humph. 
So  far  as  observed,  this  has  not  proved  serious  on  this  host. 
The  fruiting  threads  are  produced  so  meagerly  on  the  under 
surface,  that  usually  they  can  not  be  detected  by  a  hand  lens. 
See  Musk  Melon. 

Leaf  Mold,  Alternaria  Brassier  var.  nigrescens  Pegl.  See 
Musk  Melon. 


PLATE    IX. 


a.     Young  tree  with  injured  bark  at  base  dropping  its  leaves  in  July,  p.  30; 


b.     Injured  bark  studded  with 
fungous  growth.      X  2. 


c.      Health)'  bark  showing  lenticels. 
WINTER   INJURY  TO  BARK  OF  APPLE. 


PLATE    X. 


a.     Peach,  p.  341. 


Healthy. 


Injured. 


Healthy, 


b.     Apple,  p.  303. 


c.      Plum,  p.  345. 


Injured.  Health3^  Injured. 

WINTER   INJURY  TO  WOOD  OF   FRUIT  TREES, 


Healthy, 


PLATE    XI. 


a.      Black  Rot,  p.  298. 


b.      Sooty  Blotch,  p.  302. 


X  3 


X  2 


c.     Cluster  Cup  of  Rust,  p.  301.  d.      Fly  Speck,  p.  299. 

FUNGI    OF    THE    APPLE. 


I 


PLATE  XII. 


a.     On  fruit. 


Scab,  p.  301. 


X2. 


b.     On  twig. 


c.     Bitter  Rot,  p.  297.  d.      European  Canker,  p.  299. 

FUNGI   OF  THE  APPLE. 


PLATE   XIII. 


Barley. 


Bean. 


a.      Smut,  p.  306. 


b.     Downy  Mildew,  p.  307.     c.     Anthracnose,  p.  307. 


Bean. 


X  2. 


d.      liliiJclit,  p.  307.  c.      Rust,  p.  30S. 

FUNGI   OF   BARLEY  AND  BEAN, 


PLATE   XIV. 


Blackberrv. 


Beet  -h  } 


a.     Leaf  Spot,  p.  309. 
BlackberrJ^ 


b.     Leaf  Spot,  p.  309. 
Buckwheat. 


c.     Rust,  p.  309.  d-     Leaf  Blight,  p.  310. 

FUNGI  OF  BEET,  BLACKBERRY,  BUCKWHEAT. 


Cabbage. 


PLATE  XV. 
Carnation. 


a.      Club  Root,  p.  310. 
Cherr}^  X  2. 


I|r.^:^ 


ii^aw 


b.      Rust,  p.  312. 
Chr3'santhemum  X  2. 


c.      Powder  Mildew,  p.  314.  d.      Rust,  p.  315. 

FUNGI   OF   CABBAGE,   CARNATION,   CHERRY,   CHRYSANTHEMUM. 


PLATE    XVI. 

Corn.      -^  )A. 


Clover. 


a.      Rust,  p.  316. 
Currant.      X  3- 


b.      Smut,  p,  317. 


Elm  Bark.      X  2. 


c.      Red  Knot,  p.  319.  d.      White  Fungus  on  Elm-Leaf  beetle,  p.  321. 

FUNGI   OF   CLOVER,  CORN,  CURRANT,   ELM   BEETLE. 


PLATE  XVII. 


Grape. 


a.     Black  Rot,  p.  323. 


Hazel  X  2 


Hollyhock  X  2. 


b.      Downy  Mildew,  p.  324. 
Horseradish. 


c.    Black  Knot,  p.  325.       d.    Rust,  p.  326.  e.    Leaf  Spot,  p.  327. 

FUNGI   OF   GRAPE,   HAZEL,   HOLLYHOCK.   HORSERADISH. 


PLATE  XVIII. 


a.     Blighted  vine  in  the  field. 


b.      Under  surface  of  leaf  showing  dead  areas. 
BLIGHT  OR  DOWNY  MILDEW  OF   MUSKMELON,  p.  330. 


Iris. 


a.      Rootstock  Rot,  p.  327. 


Oats. 


PLATE    XIX. 

Musk  Melon. 


b.     Scab,  p.  331. 


X2  On  leaf. 


1   ■,'i'itM 

c.     Black  Rust,  p. "332. 


d.     Crown  Rust,  p.  333.  c.      Smut,  p.  32 

FUNGI    OF    IRIS,   MELON,  OATS. 


PLATE    XX. 


a.      Black  Spot,  p.  333. 
Stem  Rot,  p.  334. 


b.     End  view.  c.     Cross-section. 

FUNGI   OF   ONION. 


PLATE    XXL 


b.     Brown  Rot,  p.  337. 


a.     On  fruit. 


Scab,  p.  340. 


c.     On  twigs.      X  2. 


d.      On  leal.      x 


FUNGI   OF   PEACH, 


PLATE    XXII. 


a.     Bacterial  Rot,  p.  350. 


b.      Dry  End  Rot,  p.  349. 


c.     Scab,  p.  350.  d.      Blight,  p.  347. 

FUNGI    OF    POTATO. 


PLATE    XXIII. 


a.     Green  leaves  showing  early  stage  of  blight,      p.  347. 


b.     Todd's  blighted  field,  photographed  July  28,  1902  ;  less  than  a  week  before, 
this  field  was  perfectly  green. 

BLIGHT  OF   POTATO. 


PLATE  XXIV. 


Phlox. 


Plum. 


a.     Powder)'  Mildew,  p.  345. 
Plum. 


Raspberry. 


b.      Crown  Gall,  p.  346. 
X  2 


"  ,^|^j: 


.  ■■■  :M 


c.    Black  Knot,  p.  345.     d.    Crown  Gall,  p.  354.  e.     Cane  HIight,  p.  35; 

FUNGI   OF   PHLOX,   PLUM,   RASPBERRY, 


a.      Powder_y  Mildew,  p.  356. 


Rose. 


b.      Ergot,  p.  357. 
Strawberry. 


c.     Leaf  Blotch,  p.  355.  d.      Leaf  Spot,  p.  360. 

FUNGI   OF   ROSE,   RYE,  STRAWBERRY, 


a.     Bacterial  Wilt,  p.  359. 


b.      Black  Mold  at  base  of  blossom,  p.  358. 


c.     Metallic  Mold  on  blossom,  p.  359.      X 
FUNGI   OF   SQUASH. 


PLATE    XXVII. 


a.      Showing  area  in  A.  Urc's  loiiiaio  tiekl  where  blight  killed  man)'  plants. 


Blighted.  Healthy, 

b.     Tomato  leaves. 


i  # 


1 1  •  • 


c.  Cross  and  longitudinal  sec- 
tions of  tomato  stems.  Upper  three 
rows  blighted  ;  lower  two  rows 
healthy  stems. 


BACTERIAL   BLIGHT   OF   TOMATO,   p.  304. 


PLATE  XXVIII. 


Tomato. 


a.      Point-Rot,  p.  367- 


Turnip,  X  2 


b.     Anthracnose,  p.  364. 


Violet. 


c.     Downy  Mildew,  p.  367.  d.      Spot  Disease,  p.  368. 

Youno-  Watermelon. 


e.      Anthracnose,  ]>.  3()<). 
FUNGI   OF  TOMATO,  TURNIP,  VIOLET,  WATERMELON. 


JDfrllBjRARY  of  tl 

Agricultijtr     ' 
Colle 


State  of  Connecticut 


REPORT 


OF 


The' Connecticut  Agricultural 
Experiment  Station 

FOR   THE  YEAR  1904 

PART  IV. 
REPORT  OF  THE  STATION  BOTANIST 


CONNECTICUT 

AGRICULTURAL   EXPERIMENT 
STATION 


REPORT  OF  THE  BOTANIST 

G,  P.  CLINTON,  Sc.  D. 


I.     Notes  on  Fungous  Diseases,  etc.,  for  1904. 
II.     Down}^  Mildew,  or  Blight,  Peronoplasmopora  Ctihensis  (B.  &  C.)  Clint., 
of  INIusk  Melons  and  Cucumbers. 
III.     Down}^  Mildew,   or  "QW'^'i,  Phytophihora  infestans  {^o'!\X.)V)&^y.,   of 
Potato. 


Issued  May,  1905 


NOTES    ON    FUNGOUS    DISEASES    FOR    I9O4.  3II 

REPORT  OF  THE  BOTANIST. 


NOTES    ON    FUNGOUS    DISEASES,    ETC.,    FOR    1904. 

In  the  last  Annual  Report,  1903,  pp.  279-370,  the  writer  gave 
short  notes  on  all  of  the  fungous  and  bacterial  diseases  and 
physiological  troubles  which  had  been  observed  up  to  that  time 
on  the  cultivated  plants  of  Connecticut.  In  the  present  article 
are  given  notes  on  those  that  were  prominent  the  past  year  and 
those  that  were  much  less  conspicuous  than  during  the  two 
previous  seasons,  together  with  brief  descriptions  of  the  few 
troubles  found  in  the  state  for  the  first  time  and  additional 
information  gained  concerning  old  ones.  The  half-tone  illus- 
trations are  natural  size  unless  otherwise  stated.  On  the  whole, 
1904  was  not  conspicuous  for  serious  outbreaks  of  fungous 
troubles,  especially  when  compared  with  the  two  previous  years. 
This  was  largely  due  to  the  warmer,  drier  season. 

ALFALFA,  Medicago  sativa. 

Leaf  Spot,  Pseiidopeziza  Medicaginis  (Lib.)  Sacc.  Plate 
XVIII,  a.  Recently  further  attention  has  been  called  to  the  cul- 
tivation of  alfalfa  in  this  state  for  dairy  purposes.  While 
undoubtedly  a  valuable  plant  in  many  regions,  most  efforts  to 
raise  it  here  have  been  unsuccessful  thus  far.  In  the  Report 
for  1903,  p.  297,  attention  was  called  to  the  leaf  spot  disease 
of  this  plant.  During  the  past  season  this  disease  considerably 
damaged  a  small  plot  of  alfalfa  grown  on  the  Experiment  Sta- 
tion grounds.  Plate  XVIII,  a,  shows  the  general  appearance  of 
the  purplish  spots  it  produces  on  the  leaves,  which,  as  they 
become  badly  infected,  turn  yellowish  and  die  prematurely. 

APPLE,  Pirus  Mains. 

Powdery  Mildew,  Podosphaera  leucotricha  (Ell.  &  Ev.) 
Salm.  Plate  XVIII,  b.  As  noted  in  the  Report  for  1903,  p. 
300,  this  fungus  does  most  damage  to  nursery  stock,  occurring 
commonly  on  the  twigs.  It  is  worse  on  some  varieties  than  on 
others  and  was  found  especially  abundant  on  Rome  Beauty  in 
one  nursery  the  past  season.     The  illustration  shows  the  minute 


312         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

perithecia  crowded  together  in  dark  patches  on  the  dirty  white 
mycehum  that  enveloped  the  twigs  of  that  variety. 

RusT^  Gymnosporangium  macropus  Lk,  Plate  XVIII,  c. 
Apple  rust  was  not  as  prominent  as  usual  the  past  year.  Cer- 
tain varieties  are  known  to  be  very  susceptible  to  attack.  (See 
Report  1903,  p.  301.)  This  was  shown  very  plainly  last  spring 
in  the  Experiment  Station  disease  garden  in  the  case  of  Bechtel's 
Flowering  Crab.  A  ripe  "cedar  ball"  of  the  above  rust  was 
attached  to  the  top  of  a  young  tree  during  moist  weather  in  May. 
In  June  the  spermagonial  stage  was  very  prominent  on  the  upper 
side  of  many  of  the  leaves  to  which  had  been  carried  the  germi- 
nating sporidia  from  this  cedar  ball.  The  illustration  shows 
the  clusters  of  spermagonia  on  a  leaf  which  developed  about 
forty  separate  points  of  infection.  On  another  leaf  over  one 
hundred  distinct  spermagonial  clusters  were  counted,  while  on 
some  of  the  leaves  the  whole  surface  was  covered,  so  that  there 
was  no  separation  into  distinct  colonies.  In  July  the  aecidial 
stag'e  became  prominent  on  the  under  surface  of  these  leaves. 

Scab,  Venturia  incequalis  (Cke.)  Aderh.  This  fungus  was 
not  unusually  prominent  the  past  season.  Attention  was  called 
in  the  last  Report,  p.  301,  to  a  case  where  the  parasitic  stage, 
F itsicladiufvi  dendriticum,  was  found  on'  the  twigs  of  a  single 
nursery  tree.  Last  fall  it  was  found  again  in  another  nursery 
on  the  twigs  of  the  Fall  Pippin  and  the  leaves  of  this  variety 
were  unusually  scabby.  No  sign  of  the  asco-spore  stage  has  yet 
been  observed  on  the  twigs. 

Winter  Injury..  Mention  was  made  in  the  Report  for  1903  of 
the  injury  done  by  the  two  unusual  winters  of  1902-3  and 
1903-4.  During  the  past  summer  further  observations  have 
shown  a  number  of  young  orchards  that  suffered  severely  from 
winter  injury.  Its  effect  on  young  orchard  and- nursery  trees 
was  usually  shown  by  the  killing  or  severe  injury  of  the  wood. 
If  snow  was  on  the  ground  this  injury  only  extended  down  to 
the  snow  line.  Externally  the  trees  looked  all  right,  as  the 
bark  and  cambium  were  not  injured,  so  that  new  wood  was 
formed  during  the  summer,  but  this  annual  ring  of  growth  was 
often  very  slight.  A  cross  section  of  the  stem  showed  this  as 
a  white  growth  just  beneath  the  bark  and  around  the  blackened 
injured  wood  of  the  preceding  seasons.  Some  trees  were  killed 
outright  or  so  severety  injured  that  they  died  during  the  sum- 


NOTES    ON    FUNGOUS    DISEASES    FOR    I904.  313 

mer.  When  the  injury  did  not  extend  entirely  down  to  the 
stock,  badly  damaged  trees  were  cut  off  and  a  new  trunk  started 
from  a  bud  on  the  uninjured  part  of  the  scion.  Such  trees,  if 
properly  cultivated,  made  very  satisfactory  growth  during  the 
summer.  Where  the  injury  was  not  so  severe,  thorough 
pruning  proved  helpful. 

In  bearing  orchards  the  injury  usually  showed  itself  in  the 
bark  and  not  in  the  wood.  Usually  the  bark  was  injured 
only  at  the  base  of  the  trunk  by  a  girdled,  dead  area  extend- 
ing from  the  ground  up,  often  only  on  one  side.  Sometimes 
isolated  dead  areas  could  be  found  further  up  on  the  trunk 
or  on  the  branches.  The  younger  trees  suffered  more  severely 
and  often  in  the  summer  shed  many  of  their  leaves,  and  if 
the  trunk  was  completely  girdled  finally  died.  When  the  bark 
becomes  loosened  on  these  dead  areas  it  should  be  scraped 
off  and  the  wood  painted  over  to  prevent  rot.  For  orchard 
sites  high,  exposed  hillsides  are  preferable,  other  things  being 
equal,  to  sheltered  lowlands,  where,  in  our  experience,  winter 
injury  most  commonly  occurs.  Late  cultivation  and  exces- 
sive fertilization,  too,  are  apt  to  send  the  trees  into  winter 
with  their  wood  in  an  unripened  condition  and  thus  more  sus- 
ceptible to  injury.  Some  of  the  nurseries  of  the  state  suffered 
severely  from  winter  injury  to  stock  left  outdoors.  To  prevent 
future  trouble  from  this  source  one  firm  the  past  summer  built 
a  large  storage  house  where  all  of  the  stock  offered  for  sale  in 
the  spring  can  be  wintered  out  of  reach  of  the  cold.     See  Peach. 

ASPAEAGTIS,  Asparagus  officinalis. 

Rust,  Puccinia  Asparagi  DC.  Plate  XIX,  a-c.  This  fungus 
has  been  mentioned  before  as  doing  damage  in  this  state,  having 
been  reported  first  in  1896.  So  far,  however,  the  aecidial  stage 
(see  Report  1903,  p.  305)  has  not  been  reported.  This  was 
observed  the  past  season  in  a  certain  bed  in  Westville.  The 
bright  orange  spores  of  this  stage  are  produced  in  minute,  toothed 
cups,  embedded  usually  in  elliptical  clusters  on  the  stems.  (See 
Plate  XIX,  b.)  Compared  with  the  red  and  black  rust  stages 
of  this  fungus,  this  stage  is  infrequent  and  .harmless  (except 
as  it  serves  as  the  source  of  infection  for  these  other  stages)  and 
appears  only  in  the  spring  and  early  summer.     In  most  of  the 


314        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

plants  examined  it  was  confined  to  the  lower  twelve  inches  of 
the  stem.  In  this  particular  field  the  asparagus  had  been 
gathered  by  snapping  off  the  tender  tips,  thereby  often  leaving 
stubs  several  inches  long.  It  was  on  these  old  stubs  that  most 
of  the  aecidia  were  found.  This  method  of  removal  hence 
served  as  a  means  of  increasing  the  rust  in  the  field,  for  if  the 
asparagus  had  been  cut  off  close  to  the  ground  the  rust  would 
have  developed  only  on  a  few  of  the  old  plants.  The  reason 
why  the  aecidial  stage  usually  appears  on  the  base  of  the  plants 
is  apparently  because  infection  takes  place  from  the  black  rust 
stage  carried  over  winter  in  fragments  of  the  old  stems  in  the 
ground  and  the  bases  of  the  stems  are  the  most  favorably 
situated  portion  of  the  plant  for  infection. 

As  the  aecidial  stage  was  just  appearing  in  this  field  and  as 
there  were  few  old  plants,  the  field  having  been  severely  cropped, 
it  was  decided  to  see  if  the  subsequent  injurious  stages  of  the 
rust  could  be  kept  out  of  the  field  by  thorough  removal  of  stubs 
and  stems  showing  the  aecidial  stage,  since  the  bed  was  some- 
what isolated.  The  aecidial  stage  was  first  observed  June  14, 
but  many  of  the  aecidial  cups  were  unopened  and  the  weather 
was  not  favorable  for  the  spread  of  the  rust  from  the  mature 
ones.  June  15  to  17  the  writer  went  carefully  over  the  field, 
about  a  quarter  of  an  acre,  and  removed  all  of  the  parts  show- 
ing rust.  The  field  was  gone  over  twice  at  this  time,  as  it  was 
discovered  that  on  the  first  search  not  all  of  the  rust  was  found. 
In  all  858  rusted  stubs  (chiefly)  and  stems  were  removed. 
There  was  no  sign  whatever  of  either  the  red  or  black  rust  stage 
at  this  time.  On  June  27  the  field  was  again  examined  and  38 
stems  and  stubs  were  removed.  Of  these,  however,  11  showed 
the  red  rust  (uredo)  stage,  though  not  abundantly.  (See  Plate 
XIX,  c.)  These  were  chiefly  on  the  lower  parts  of  the  plants 
and  were  just  beginning  to  split  open  to  shed  their  spores.  They 
were  also  mostly  confined  to  plants  showing  the  aecidial  stage. 
The  field  was  examined  a  third  time  on  July  11  and  192  stems 
were  removed.  As  many  of  these  were  large  plants,  further 
removal  was  impossible  without  injury  to  the  bed.  Then,  too, 
the  uredo  stage  had  become  quite  common  at  this  date  and  a  few 
teleuto  sori  (black  rust)  were  also  present.  Lest  than  half  the 
stems  removed  showed  the  aecidial  stage.  It  is  quite  probable 
that  not  all  of  the  plants  showing  the  uredo  stage  were  cut  at 


NOTES    ON    FUNGOUS    DISEASES    FOR    I904.  315 

this  time,  as  in  large  plants  the  scattered  outbreaks  were  easily 
overlooked.  August  4  the  field  was  examined  again  and  the 
uredo  stage  was  found  rather  common  through  it.  About  Sep- 
tember 23  the  field  was  mowed  and  the  tops  raked  together, — 
not  very  carefully, — and  burned.  The  field  was  not  examined 
until  after  this  was  done,  so  the  relative  amount  of  rust  present 
at  this  time  was  not  determined.  It  is  easily  seen  from  what 
has  been  stated  that  this  removal  of  the  aecidial  stage  did  not 
prevent  the  uredo  stage  at  least  from  becoming  fairly  abundant 
in  the  field.  What  effect  this  removal,  coupled  with  the  burn- 
ing of  the  canes  in  the  fall,  will  have,  remains  to  be  seen  another 
year.  That  the  very  careful  removal  and  burning  of  all  of  the 
tops  and  litter  in  the  fall  for  several  years  helps  to  decrease 
the  rust,  if  the  patch  is  isolated,  has  been  shown,  apparently,  in 
a  small  bed  at  the  Experiment  Station.  In  1896  Dr.  Sturgis 
first  observed  the  rust  in  this  bed.  Beginning  about  1897,  and 
for  at  least  four  years,  the  tops  and  litter  from  this  bed  were 
removed  and  burned.  The  rust  has  gradually  become  less,  until 
last  season  none  whatever  was  found  in  it. 

Rust  Parasite,  Darluca  Fihmi  (Biv.)  Cast.  Plate  XIX,  d. 
This  fungus  is  parasitic  on  the  rust  fungus,  and  so  is  bene- 
ficial in  checking  the  latter.  It  was  very  abundant  in  the 
field  described  above.  Unquestionably  it  prevented  many  of  the 
aecidial  ciips  from  maturing  their  spores.  The  fruiting  recep- 
tacles of  this  fungus  appear  in  the  illustration  as  minute  black 
dots  covering  the  area  infested  by  the  rust.  The  same  fungus 
also  is  common  here  on  the  uredo  and  teleuto  stages  of  the 
asparagus  rust.  In  one  field  observed  the  past  year  that  had 
been  killed,  apparently,  by  the  rust,  this  parasite  was  much  more 
conspicuous  than  the  rust  itself.  Probably  in  this  case  the  fun- 
gus was  parasitic  on  the  hidden  mycelium  of  the  rust  and  largely 
prevented  its  spore  formation,  so  that  the  parasite,  rather  than 
the  rust,  appeared  to  be  doing  the  harm.  It  is  barely  possible, 
however,  that  to  some  degree  the  parasite  was  really  intruding 
on  the  host  without  the  aid  of  the  rust  and  so  was  responsible 
for  part  of  the  injury.  This  same  parasite  occurs  on  a  number 
of  other  rust  species  in  this  state ;  for  example,  carnation  rust 
and  blue-grass  rust. 


3l6         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

BEANS  (LIMA),  PJias coins  lunatus. 

Bacterial  Spot.  Plate  XX,  a.  The  cotyledons  of  the  lima 
bean  at  the  time  the  seedlings  appear  above  ground  often  show 
purplish  discolored  areas  that  develop  into  sunken  spots,  as  is 
shown  in  the  illustration.  Microscopical  examination  of  these 
in  their  young  state  generally  reveals  bacteria  present  before 
the  fungi  which  later  often  fruit  at  these  places ;  while  without 
positive  evidence,  these  cankered  areas  seem  to  be  one  of  the 
sources  of  infection  of  the  bacterial  disease  which  later  in  the 
season  often  appears  on  the  leaves  as  reddish  bordered  spots 
(Report  1903,  p.  307)  and  does  considerable  injury. 

CABBAGE,  Brassica  oleracea. 

Downy  Mildew^  Peronospora  parasitica  (Pers.)  Tul.  This 
fungus  has  been  reported  before  on  other  cruciferous  plants, 
but  was  observed  for  the  first  time  last  spring  on  young  cabbage 
plants  grown  in  a  hot-bed.  The  trouble  did  not  continue  after 
the  plants  were  set  in  the  field,  and,  no  doubt,  was  induced  by 
too  moist  and  crowded  condition  of  the  plants  in  the  bed. 

CHEEEY,  Primus  avium. 

Brown  Rot^  Sclerotinia  fructigena  (Pers.)  Schrot.  Plate 
XX,  b.  A  specimen  of  Governor  Wood  cherry  in  the  Experi- 
ment Station  grounds  seems  to  be  especially  subject  to  this  rot 
year  after  year.  In  1904  the  disease  showed  very  early  on 
the  perfectly  green  fruit.  An  examination  indicated  that 
the  curculio  or  other  puncturing  insects  had  considerable  to  do 
with  spreading  it,  as  often  the  infected  fruit  showed  signs  of  a 
sting  and  the  trouble  was  almost  as  bad  while  the  fruit  was  green 
as  it  was  later  when  the  fruit  was  ripe  and  more  easily  infected. 
Some  of  the  blossoms  were  also  infected,  but  no  diseased  twigs 
were  found,  though  careful  search  was  not  made  for  them.  The 
tree  had  been  sprayed  during  the  winter  with  lime  and  sulphur, 
which  still  covered  it  rather  thoroughly,  but  this  apparently  had 
no  influence  in  keeping  down  the  rot,  as  one  might  suppose  it 
would  if  it  started  first  from  spores  produced  on  the  twigs.  A 
careful  search  has  been  made  for  three  years  for  the  Sclerotinia 
stage  en  the  old  cherry  pits  lying  on  the  ground,  but  this  has 
never  been  found.     Very  few  mummies  remain  hanging  on  the 


NOTES    ON    FUNGOUS    DISEASES    FOR    I904.  31/ 

tree  at  the  beginning  of  spring,  though  their  pedicles  more  often 
remain  attached.  The  illustration  shows  that  the  disease  often 
kills  these  pedicles,  sometimes  producing  spores  on  their  upper 
end.  It  was  thought  that  possibly  the  fungus  was  perpetuated 
by  its  mycelium  passing  down  the  diseased  pedicles  into  the 
fruiting  spurs  and  then  up  into  the  flowers  in  which  it  was  found 
in  the  spring.  Examination  of  the  fruiting  spurs  in  the  winter 
showed  that  often  those  having  the  old  pedicles  attached  were 
dead,  while  cross  sections  of  others  revealed  reddish  discolora- 
tion of  the  tissues.  Rough  microscopic  sections  of  these  showed 
that  often  many  of  the  parenchyma  cells  of  the  bark  and  pith 
were  dead  or  severely  injured,  but  there  was  no  evident  indi- 
cation of  mycelium,  and  when  diseased  or  dead  spurs  were 
placed  in  a  moist  chamber  or  diseased  tissue  from  them  was 
inserted  in  Petrie  dishes  of  agar  agar  no  development  what- 
soever of  the  Monilia  fungus  took  place.  On  the  other  hand, 
when  the  mummied  fruit  and  diseased  pedicles  were  placed  in 
the  moist  chamber  the  production  of  the  Monilia  spores  was 
abundant.  These  observations,  then,  indicate  that  the  fungus 
does  not  travel  down  the  diseased  pedicles  and  from  these  infest 
the  fruit  spurs,  but  that  the  infection  each  spring  comes,  as 
ordinarily  supposed,  either  from  the  mummied  fruit  (and 
pedicles)  or  infected  branches,  in  which  the  Monilia  spores  are 
again  produced  in  early  spring  during  moist  weather,  and  from 
these  carry  the  disease  first  to  the  blossoms  and  from  them  to 
the  young  fruit,  their  infection  of  the  latter  being  largely  aided 
by  puncturing  insects.  The  influence  of  a  puncture  on  the  fruit 
was  shown  with  green  cherries,  kept  in  a  moist  chamber  in  the 
laboratory,  in  which  the  spores  of  the  fungus  were  inserted 
through  a  needle  puncture.  These  cherries  started  to  rot  imme- 
diately at  the  punctured  places,  while  others  with  spores  placed 
on  them  without  puncture  and  checks  with  no  spores  placed 
on  them,  though  rotting  later,  usually  started  at  some  other 
point  than  where  the  spores  were  placed,  probably  from  some 
injured  place  in  the  skin  where  spores  had  previously  lodged. 

CORN,  Zea  Mays. 

Leaf  Blight^  H elminthosporium  turcicum  Pass.  This  fun- 
gus, which  was  so  injurious  in  1903,  did  practically  no  damage 
the  past  season,  thus  showing  that  it  is  to  be  feared  only  in  very 
moist  seasons  when  the  corn  naturally  does  poorly. 


3l8         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

CUCUMBER,  Cucumis  sativus. 

Downy  Mildew,  Plasmopara  Cubensis  (B.  &  C.)  Humph. 
Not  injurious  this  season.     See  Musk  Melon. 

DEWBERRY,  Ricbus  Canadensis. 

Orange  Rust  Parasite,  Tuber ctdina  persicina  (Ditm.) 
Sacc.  Plate  XXI,  a.  This  fungus,  especially  in  the  west,  is 
a  common  parasite  of  various  rusts.  Here,  on  the  orange  rust, 
it  does  not  form  the  dusty  purplish  spores  of  the  Hyphomycetous 
stage  so  conspicuously  as  it  does  later  the  subspherical  sterile 
purplish  sclerotia  (See  illustration.)  There  is  little  doubt  that 
if  these  were  properly  developed  they  would  reveal  the  existence 
of  an  asco-spore  stage  as  yet  unknown.  It  is  questionable 
whether  the  fungus  is  of  any  practical  use  here  in  keeping 
the  orange  rust  in  check. 

EGG  PLANT,  Soianum  Melongena. 

Wilt^  Fusarium  sp.  Plate  XXI,  b.  The  cause  of  this 
trouble  has  not  been  determined  definitely,  though  it  is  probably 
a  Fusarium  fungus.  It  was  present  again  the  past  year  in  some 
of  the  fields  of  this  plant.  Infected  plants  showed  a  dwarfed, 
yellowish  appearance,  and  produced  little  and  inferior  fruit. 
Late  in  the  season  an  examination  of  the  badly  diseased  plants 
showed  that  the  stem  and  roots  under  ground  were  badly  rotted, 
as  shown  in  the  illustration.  As  was  expected,  spraying  pro- 
duced no  favorable  results  with  this  trouble.  There  is  no 
question  that  the  disease  begins  in  the  very  young  plants,  prob- 
ably always  in  the  seed  bed,  though  it  may  not  show  plainly  at 
this  time,  and  starts  from  infected  soil  or  diseased  seed.  Care, 
therefore,  when  possible,  should  be  used  to  select  the  very  best 
seed  from  undiseased  plants  and  to  use  fresh  soil  in  the  seed 
beds. 

EIG,  Ficus  Carica. 

Smutty  Mold,  Sterigmatocystis  Ficuum  (Reich.)  P.  Henn. 
Plate  XXI,  c.  This  smutty  mold  has  been  unusually  common 
the  past  season  in  the  market  figs.  The  spores  of  the  fungus 
partially  fill  the  interior  of  the  figs  with  a  black  smutty  mass  so 
much    like    the    true    smuts    that    the    fungus    was    originally 


NOTES    ON    FUNGOUS    DISEASES    FOR    I9O4.  319 

described  as  one  of  these.  It  belongs,  however,  under  the 
Hyphomycetes,  or  imperfect  fungi.  The  same  or  a  similar 
fungus  also  occurs  in  dates,  but  has  not  yet  been  reported  in 
this  state,  though  probably  not  uncommon  in  the  markets. 


GRAPE,  Vitis  sps. 

Powdery  Mildew^  Uncinula  necator  (Schw.)  Burr.  Plate 
XXII,  a-c.  The  powdery  mildew  of  grapes  was  unusually 
abundant  last  fall,  becoming  especially  prominent  on  the  fruiting 
stems  and  the  berries.  It  did  not  seem  to  cause  unusual  injury, 
however,  except  where  it  occurred  on  the  thin-skinned  varieties, 
especially  the  white  varieties,  in  which  the  berries  were  more  or 
less  wiltedj  besides  being  somewhat  disfigured  by  the  presence 
of  the  fungus.  The  illustrations  show  the  minute  black  peri- 
thecia,  or  spore ,  receptacles,  very  abundantly  scattered  or  clus- 
tered in  the  superficial  whitish  mycelium  that  covers  various 
parts  of  the  host.  Suggestions  for  treatment  were  given  in  the 
Report  for  1903,  p.  324. 

MULBERRY,  Morus  sp. 

Bacterial  Disease,  Bacillus  Cuhonianus  Macch.  {Bacterium 
Mori  Boy.  &  Lamb.)  Plate  XXIII,  a-b.  This  disease  was 
found  in  the  state  for  the  first  time  in  one  of  the  nurseries, 
where  it  was  causing  more  or  less  injury  to  the  young  trees. 
Upon  the  leaves  the  disease  shows  as  small  reddish  brown  spots, 
when  moist  often  semi-pellucid,  that  penetrate  through  the 
tissues  to  both  surfaces.  These  are  often  more  prominent  and 
numerous  than  is  shown  in  the  illustration.  The  chief  injury 
in  this  nursery,  however,  was  to  the  twigs.  Many  of  the 
branches  and  even  whole  young  trees  had  a  stunted,  yellowish 
appearance.  Usually  the  cause  could  be  traced  somewhere  on 
the  stem  to  an  evident  canker,  like  those  shown  in  the  illustra- 
tion, which  more  or  less  completely  girdled  the  stem.  As 
these  diseased  areas  in  the  bark  become  older,  the  growth  of 
the  tissues  often  tends  to  cut  them  off  from  further  develop- 
ment, so  that  they  show  merely  as  a  rough  or  corky  superficial 
spot  in  the  bark.  When  the  disease  penetrates  to  the  cambium, 
however,  the  disease  usually  spreads  internally  between  the  bark 


320         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

and  wood,  doing  considerable  injury  to  each;  see  cut  end  of 
the  largest  branch  in  the  illustration.  This  diseased  condition, 
then,  may  not  show  exteriorly  except  through  the  yellowish, 
sickly  growth.  Sometimes  the  trouble  becomes  so  bad  that  the 
young  stem  can  be  easily  snapped  off  at  the  diseased  place. 
This  disease  was  first  described  from  Italy  and  France  and  has 
been  observed  by  the  writer  in  Illinois  on  both  cultivated  and 
wild  species  of  the  mulberry.  Probably  the  best  treatment  is 
to  thoroughly  prune  out  the  disease  in  winter  time,  as  is  done 
for  pear  blight. 

MUSK  MELON,  Cucumis  Melo. 

Bacterial  Rot.  Plate  XXIII,  c.  A  bacterial  rot  of  the 
fruit  was  not  uncommon  in  some  of  the  musk  melon  patches 
the  past  summer.  It  seems  to  have  been  caused  by  the  same 
organism  that  produces  the  wilt  of  the  vines,  or  at  least  this 
may  have  been  its  starting  point.  The  fruit  developes  a  soft 
internal  rot,  without  external  evidence  in  the  youngest  stages, 
but  eventuall}^  it  spreads  to  the  exterior,  especially  on  the  side 
next  the  ground.  Some  melons  were  found  in  which  the  bac- 
teria were  limited  to  the  bundles  in  the  peduncle  and  to  those 
in  the  interior  of  the  fruit,  the  surrounding  tissues  being  healthy 
as  yet,  thus  suggesting  its  relationship  to  the  bacterial  wilt,  which 
was  also  found  in  these  fields.  Vines  that  were  thoroughly 
sprayed  several  times  during  the  season  developed  the  rot  in 
the  fruit  as  badly  as  those  not  sprayed. 

Downy  Mildew  (Blight),  Plasmopara  Cubensis  (B.  &  C.) 
Humph.  This  trouble,  which  has  been  so  common  and  injurious 
during  several  seasons  past,  was  very  uncommon  the  past  year, 
so  far  as  the  writer  observed  doing  no  damage  whatever.  In 
1903  its  diminishing  injury  and  later  appearance  was  reported 
by  the  writer  and  the  prediction  made  that  it  was  on  the  wane. 
In  1904  for  the  first  time  in  several  years  a  fair  crop  of  musk 
melons  Avas  obtained.  This  was  largely  due  to  the  drier,  warmer 
summer,  which,  besides  keeping  this  fungus  in  check,  was 
responsible  for  a  vigorous  growth  of  vines  so  necessary  for  the 
production  of  fruit  in  this  crop.  (See  special  article  on  this 
blight  in  the  present  Report.) 


NOTES    ON    FUNGOUS    DISEASES    FOR    I904.  321 

ONION,  Allium  Cepa. 

Stem  Rot,  Botrytis  sp.  Plate  XXIV,  a-b.  The  stem  rot 
trouble  of  the  Southport  White  Globe  onions  (see  Report,  1903, 
p.  334),  which  was  so  bad  the  two  previous  years,  did  no  damage 
in  1904.  As  was  suggested  in  the  last  Report,  this  trouble 
is  largely  induced  by  unusually  wet  seasons,  especially  during 
July  and  August.  These  months,  in  1904,  being  considerably 
drier  than  those  of  the  two  previous  years,  were  thus  unfavora- 
ble for  the  development  of  the  fungus.  No  signs  of  it  whatever 
was  found  on  plants  in  the  field  and  no  especial  complaint  of  the 
rotting  of  the  stored  onions  was  made  by  the  growers.  Where 
planted,  this  variety  did  fairly  well  last  season,  except  for  the 
injury  of  the  onion  maggot,  which  was  unusually  common  on 
all  onions.  Many  growers,  however,  were  so  disheartened  by 
the  losses  of  the  previous  seasons  that  the  acreage  devoted  to 
this  variety  was  very  much  smaller  than  usual.  So  far,  the 
writer  has  been  unable  to  find  any  Sclerotinia  stage  connected 
with  this  fungus.  The  selerotia  which  often  develop  in  the 
rotting  tubers  and  carry  the  fungus  over  the  winter  apparently 
develop  only  the  Botrytis  stage,  v/hich  causes  the  injury  in  the 
field  and  store  house.  Plate  XXIV,  b,  shows  an  old  onion, 
gathered  outdoors  in  the  spring,  with  several  of  these  black 
sclerotial  bodies. 

Not  being  able  to  predict  the  character  of  the  season  as  to  its 
moisture,  experiments  to  determine  the  value  of  spraying  in  pre- 
venting stem  rot  in  White  Globe  onions  were  undertaken  the 
past  year  on  the  farm  of  W.  H.  Burr  at  Green's  Farms.  As  it 
turned  out,  there  was  no  stem  rot,  so  no  information  regarding 
the  value  of  this  treatment  for  the  rot  was  gained,  yet  some 
points  of  value  regarding  spraying  onions  were  obtained.  Four 
or  five  treatments  were  planned,  but  on  account  of  sickness  only 
three  were  made,  on  June  24th,  July  5th,  and  August  3d.  Dif- 
ferent plots  of  the  onions  were  sprayed  once,  twice,  three  times 
and  not  at  all.  Onions  are  planted  so  closely  together  in  the 
fields  that  no  apparatus  drawn  by  a  horse  can  be  used.  In  this 
experiment  knapsack  sprayers  were  used.  These,  however,  are 
so  cumbersome  that  they  meet  with  little  favor  where  any  con- 
siderable spraying  is  to  be  done.  The  small  barrel  pump, 
mounted  on  wheels  somewhat  higher  than  usual,  to  bring  the 
bottom  of  the  barrel  nearly  clear  of  the  tops  of  the  onions,  no 
doubt   would   be  the   best   apparatus   where   any   considerable 


322         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

spraying  is  to  be  done.  One  man  can  then  pump  and  pull  the 
barrel  and  another  spray  several  rows  of  onions  as  they  go 
along.  The  first  treatment  need  not  be  made  before  the  first 
week  in  July,  since  the  plants  are  rather  small  before  this  time, 
and  there  is  little  danger  of  fungus  troubles  until  then.  It  is 
very  difficult  to  make  Bordeaux  mixture  adhere  to  onions  be- 
cause there  is  very  little  surface,  but  chiefly  because  of  the 
very  smooth,  glaucous  character  of  this  surface.  This  makes 
it  almost  necessary  to  use  resin  Bordeaux  to  secure  fair  results. 
Soap  added  to  the  ordinary  Bordeaux  proved  of  little  value. 
Even  with  resin  Bordeaux  the  glaucous  character  of  the  tops 
prevents  the  spray  from  adhering  any  length  of  time  if  there 
is  rainy  weather.  This  being  the  case,  at  least  four  or  five 
sprayings  will  be  necessary  to  secure  moderate  protection  against 
any  serious  fungous  trouble.  With  all  these  difficulties  and 
objections  it  is  not  likely  that  spraying  onions  against  fungous 
trouble,  unless  very  serious,  will  come  into  very  general  use. 
The  onions  sprayed  in  this  experiment  were  stored  separately, 
but  very  little  difference  was  noticed  in  their  keeping  qualities, 
and  no  true  stem  rot  developed. 

PEACH,  Prunus  Persica. 

Brown  Rot,  Sclerotinia  fructigena  (Pers.)  Schrot.  Plate 
XXIV,  c-d.  Because  of  the  light  crop  for  two  years  the  brown 
rot  of  peach  was  not  especially  prominent.  Search  last  spring 
brought  to  light,  for  the  first  time  in  this  state,  the  presence 
of  the  Sclerotinia,  or  asco-spore  stage  (see  illustrations)  on 
the  old  mummies  partly  buried  in  the  ground.  While  these 
were  not  very  common,  they  were  found  on  both  peach  and 
plum  mummies,  and  are  no  doubt  more  common  when  more  of 
the  rotten  fruit  is  left  on  the  ground.  They  serve  as  another 
means  of  infecting  the  young  blossoms  in  the  spring  and  thereby 
spreading  the  trouble  to  the  fruit. 

Frosty  Spots.  In  August  there  were  sent  to  the  Experiment 
Station  from  Cannon  Station  diseased  leaves  of  peach  which 
showed  in  their  first  stage  a  purplish  discoloration  of  the  under 
surface  and  later  a  silver  grey  color  as  if  mildewed.  Sections 
of  the  diseased  leaves,  however,  showed  no  fungus  present,  but 
did  show  that  the  epidermal  cells  and  later  the  spongy  paren- 
chyma cells  beneath  had  turned  purplish,  finally  lost  their  con- 
tents and  collapsed.     The  injury,  apparently,  was  a  physiologi- 


NOTES    ON    FUNGOUS   DISEASES    FOR    I904.  323 

cal  trouble  caused  by  some  unusual  disturbance  of  natural 
conditions.  Possibly  it  was  due  to  insufficient  water  supply 
brought  about  through  winter  injury  to  the  roots.  Lack  of 
water  as  a  cause  was  suggested  by  the  trouble  showing  first 
in  the  vicinity  of  the  bundles,  through  which  the  water  is 
brought,  and  by  its  occurrence  on  the  under  surface  of  the 
leaf  where  the  stomates  are,  which  regulate  the  transpiration 
of  the  water.  A  very  similar  trouble  was  noted  in  the  Report 
for  1903,  p.  360,  on  strawberry  leaves. 

Winter  Injury.  Many  peach  orchards  were  severely  hurt  by 
the  winter  of  1903-4.  In  most  cases  the  wood  was  injured, 
usually  down  to  the  snow  line,  as  shown  by  the  darker  color, 
without  damage  to  the  bark  and  cambium.  Many  trees  had  been 
similarly  injured  the  year  before,  and  so  formed  very  little 
new  wood  the  past  season.  Occasionally  the  trunks  of  older 
trees  were  split  toward  their  base  with  prominent  longitudinal 
cracks.  In  one  orchard  the  injury  was  confined  chiefly  to  the 
roots  of  certain  trees.  In  the  spring  these  trees  put  out  a 
scanty,  yellowish,  sickly  foliage.  Examination  showed  the 
trunks  generally  healthy,  but  the  roots  injured  or  dead.  The 
innermost  vertical  roots  were  always  least  injured,  as  they  were 
more  protected  than  the  outer  more  horizontal  roots.  Appar- 
ently only  those  trees  had  suffered  where  the  snow  had  blown 
off  the  most  exposed  places  in  the  orchard,  which  was  on  a 
hill  side.  Many  growers  in  the  spring  severely  trimmed  their 
trees  and  dug  out  those  very  badly  injured.  Undoubtedly  the 
peach  can  stand  severe  winter  injury  to  its  wood  and  still  make 
a  slight  growth  of  new  wood  the  next  year.  Just  what  the 
ultimate  value  of  these  trees  will  be,  however,  is  a  point  not 
yet  settled.  So  far  as  observed  by  the  writer,  trees  that  were 
•  injured  did  better  when  severely  pruned  than  when  not  pruned. 
See  apple,  also  Report,  1903,  p.  341. 

PEAR,  Pirns  communis. 

Scab,  Venttma  pirijia  CLih.)  Aderh.  Plate  XXV,  a-c.  This 
disease  was  not  especially  bad  the  past  season,  but  is  mentioned 
because  the  scab  stage  was  found  on  the  twigs  of  certain  trees ; 
see  illustration.  The  occurrence  of  the  fungus  on  the  twigs 
is  more  common  with  pear  than  with  apple  scab.  In  the  cases 
examined,  the  bark  was  more  or  less  corroded  or  pustular  at 
the  infected  places.     Usually  the  outbreaks,  especially  in  a  fruit- 


324         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

ing  condition,  were  found  only  on  tlie  one  and  two-year-old 
twigs.  On  the  older  twigs  apparently  the  diseased  bark 
gradually  sloughed  off  and  was  replaced  by  a  healthy  growth. 
There  was  some  indication  that  the  mycelinum  passed  from  last 
year's  to  this  year's  twigs,  since  on  the  latter  the  outbreaks 
often  appeared  first  and  most  abundantly  at  their  basal  end. 
Undoubtedly,  however,  new  infections  often  and  possibly  always 
take  place  by  reinfection  of  the  young  twigs  from  spores  pro- 
duced on  the  older.  In  the  winter  time  the  scab  areas  may 
show  plenty  of  the  spore-bearing  mycelium,  but  no  spores, 
which  begin  to  form  early  in  the  spring.  Certain  varieties 
are  known  to  scab  much  worse  than  others,  and  in  these  cases 
it  is  probably  largely  because  the  fungus  readily  becomes  estab- 
lished on  the  twigs.  This  being  the  case,  spraying  the  dormant 
wood  in  the  spring  should  have  some  effect  in  retarding  and 
lessening  the  trouble.  Observations  made  on  certain  trees 
sprayed  last  winter  with  lime  and  sulphur  showed  them  freer 
the  following  summer  from  scab  than  usual,  probably  for  this 
reason. 

PLTJM,  Prunus  sps. 

Brown  Rot,  Sclerotinia  fructigena  (Pers.)  Schrot.  The 
Sclerotinia  stage  was  found  for  the  first  time  in  this  state  on 
the  mummied  fruit  half  buried  in  the  ground.     See  peach. 

POTATO,  Solanum  tuberosum. 

Bacterial  Disease, (?)  Bacillus  Solanacearum  Sm.  Plate 
XXVII,  a-b.  The  bacterial  disease  of  potato  stems  mentioned 
in  the  Report  of  1903,  p.  351,  was  found  again  this  season. 
This  trouble  appears  early  in  June.  Usually  a  plant  here  and 
there  in  the  field  is  injured,  but  the  disease  does  not  seem  to 
spread  as  the  season  advances.  Diseased  plants  can  usually  be 
identified  by  their  yellowish  foliage  and  often  dwarfed  growth. 
Very  badly  diseased  plants  can  be  pulled  easily  from  the  soil,  the 
underground  stem  being  rotted  (Plate  XXVII,  a)  and  few  roots 
or  tubers  are  developed.  Sometimes  these  stems  look  as  if 
attacked  by  borers,  the  pith  within  being  rotted  and  hollowed 
out  for  some  distance.  Above  the  rotted  part  cross  sections 
of  the  green,  apparently  healthy,  stem  usually  show  the  bundles 
darkened  and  diseased  when  the  rest  of  the  tissues  are  healthy ; 
see  Plate  XXVII,  b.     In  these  bundles  there  is  found  an  abun- 


NOTES    ON    FUNGOUS    DISEASES    FOR    I9O4.  325 

dance  of  bacteria.  The  Rhizoctonia  fungus  sometimes  girdles 
places  on  the  underground  stem  (see  Plate  XXVI,  b)  and  may 
easily  be  confused  with  this  trouble.  The  disease  is  apparently 
the  southern  tomato  blight,  described  on  tomatoes  and  potatoes 
in  last  year's  report.  Whether  this  trouble  subsequently  devel- 
opes  as  the  common  soft  rot  of  the  tubers  is  a  question  not 
settled  in  the  writer's  mind.  If  so,  it  then  becomes  a  serious 
disease  in  this  state. 

Downy  Mildew  (Blight),  Phytophthora  infestans  (Mont.) 
DeBy.  This  trouble  was  very  late  in  appearing  and  did  no 
damage  to  the  foliage  of  early  varieties  and  but  little  to  the 
late.  The  tubers,  especially  of  the  late  varieties,  however,  rotted 
very  badly.  (See  special  article  in  this  Report  on  the  potato 
blight.) 

Rhizoctonia  (Rosette),  Corticium  vagitni  var.  Solani  Burt. 
Plate  XXVI,  a-c.  Last  spring  the  small  black  sclerotia  of  the 
sterile  Rhizoctonia  stage  of  this  fungus  were  very  common  on 
tubers  used  for  seed ;  Plate  XXVI,  a.  Again  this  spring,  1905, 
the  seed  tubers  were  abundantly  covered  with  these  sclerotia. 
Such  tubers  if  used  for  seed  will  yield  a  crop  similarly  infected, 
just  as  do  scabby  tubers,  as  was  shown  last  season  in  a  small 
experiment  with  infected  and  free  tubers.  So  far  as  appear- 
ance goes,  these  sclerotia  do  very  little  harm  since  they  are 
rather  obscure  and  often  resemble  dirt.  They  become  evident 
when  one  attempts  to  wash  the  tuber,  as  they  do  not  wash  off 
and  the  water  brings  out  more  strongly  the  contrast  between 
their  black  color  and  that  of  the  skin.  An  examination  of  the 
fields  early  in  June  showed  the  fungus  present,  the  Corticium, 
or  fruiting  stage  (Plate  XXVI,  c)  being  found  then  for  the  first 
time  in  this  state.  The  mycelium,  developed  from  the  scle- 
rotia, certainly  grows  out  on  the  young  stems  and  roots. 
Sometimes  it  produces  diseased  or  girdled  areas,  as  shown  in 
Plate  XXVI,  b.  When  the  mycelium  reaches  the  stem  just  at  the 
surface  of  the  ground,  it  developes  for  a  short  distance  a  more 
abundant  but  still  rather  inconspicuous  greyish  mealy  growth. 
This  is  the  fruiting  or  Corticium  stage  and  no  injury  is  done 
to  the  stem  here,  as  the  fungus  does  not  penetrate  the  tissues,  but 
loosely  covers  the  stem  with  a  coating  that  gradually  wears  off 
as  the  spores  are  matured,  and  eventually  disappears.  Several 
fields  were  examined  which  showed  from  15  to  20  per  cent,  of 
the  plants  having  the  Corticium  stage  on  some  of  their  stalks. 
26 


326        CONNECTICUT   EXPERIMENT    STATION   REPORT,    I904. 

Apparently  the  plants  did  not  suffer  so  severely  from  the 
fungus  as  some  writers  claim  they  do  elsewhere.  However, 
the  relative  injury  caused  here  by  this  fungus  is  a  subject  that 
needs  further  attention,  since  with  the  parts  attacked  occurring 
under  ground  the  injury  and  cause  can  easily  escape  notice. 
See  Report,  1903,  p.  350,  for  further  description  and  treatment. 

In  the  writer's  opinion  there  is  no  doubt  that  the  Corticium 
stage  is  the  same  fungus  described  by  Prillieux  and  Delacroix 
of  France  [Soc.  Myc.  7:220]  in  1891,  as  Hypochnus  Solani. 
They  did  not  recognize  its  relation  to  the  Rhizoctonia  stage, 
Rhizoctonia  Solani  Kiihn,  which  has  been  known  in  Europe 
for  some  time. 

Scab,  Oospora  scabies  Thaxt.  Considerable  complaint  was 
made  of  the  damage  caused  by  this  fungus,  which  was  unusually 
prevalent  in  1904.     See  Report,  1903,  p.  350,  for  treatment. 

PRIVET,  Ligustrvim  Japonicum. 

Winter  Injury.  Plate  XXVII,  c.  The  California  privet 
hedges  were  generally  injured  by  the  severe  winter  of  1903-4. 
In  most  cases  the  stems  were  killed  down  to  about  a  foot  from 
the  ground.  This  injury  apparently  extended  down  to  the 
snow  line,  which  completely  protected  the  parts  below,  since 
young  hedges  less  than  a  foot  high  were  not  injured  at  all. 
There  was  some  question  among  owners  of  these  hedges  as 
to  what  treatment  should  be  given  them.  The  best  treatment, 
apparently,  is  to  wait  until  the  new  growth  begins  to  start  in 
the  spring  and  then  trim  back  evenly  to  the  uninjured  portion. 
Plate  XXVII,  c,  shows  an  injured  hedge  on  the  Experiment  Sta- 
tion ground  after  the  new  growth  had  made  a  fair  start  and 
illustrates  the  trimming  necessary  in  this  case  to  remove  the 
injured  stems.  As  the  roots  of  the  hedges  were  rarely  injured, 
the  plants,  when  properly  trimmed,  made  so  vigorous  a  growth 
that  often  by  midsummer  all  indication  of  injury  had  been 
obliterated. 

RADISH,  Raphanus  sativus. 

Root  Rot,  Rhizoctonia  sp.  Plate  XXVIII,  a,  shows  speci- 
mens, received  from  Elmwood,  of  greenhouse  radishes  that 
were  severely  injured  by  a  dampening  off  and  root  rot  trouble. 
This  was  caused  by  the  sterile  mycelium  of  a  Rhizoctonia  fungus 
which  undoubtedly  becomes  established  in  the  soil,  and  when 


NOTES    ON    FUNGOUS    DISEASES    FOR    I904.  327 

this  is  kept  damp  injures  the  underground  parts  of  various 
plants.  It  is  quite  probable,  for  instance,  that  the  stem  rot 
of  rhubarb,  mentioned  later,  and  possibly  even  the  Rhizoctonia 
of  the  potato,  is  caused  by  this  same  fungus.  In  the  Experi- 
ment Station  greenhouse  certain  specimens  of  the  cigar  plant 
have  been  injured  recently  by  a  similar  agent.  In  previous 
years  other  greenhouse  plants  have  been  attacked.  Last  spring 
young  radishes  in  the  New  Haven  market  not  infrequently  had 
conspicuous,  but  shallow,  injured  spots  on  them  which  appar- 
ently had  also  been  caused  by  the  Rhizoctonia  fungus.  See 
Report  1903,  p.  345. 

RASPBEREY,  Rubus  sps. 

WiLT^  Leptosphaeria  Coniothyrium  (Fckl.)  Sacc.  For  three 
years  a  small  patch  of  berries  at  North  Haven  has  been  injured 
by  a  wilt  of  the  fruiting  stems,  which  wither  and  die  just  as  the 
berries  begin  to  mature.  The  trouble  has  increased  in  severity, 
killing  out  most  of  the  Palmers  on  which  it  started  and  finally 
appearing  on  the  Kansas  variety,  several  rows  removed.  The 
trouble  apparently  is  caused  by  the  above  fungus  girdling  the 
stems  or  producing  dead  areas  on  them.  Last  May  the  para- 
sitic pycnidial  stage  and  the  saprophytic  asco-spore  stage  were 
both  found  on  the  stems.  The  former  was  especially  abundant 
on  the  tips  of  the  pruned  stems.  Probably  this  trouble  is  not 
uncommon  in  the  state,  though  not  often  reported.     See  Report 

1903,  P-  355- 

Winter  Injury.  Complaint  was  made  by  one  grower  that 
part  of  his  raspberries  had  leaved  out  in  the  spring,  but  after- 
ward had  sickened  and  died.  Examination  of  specimens 
received  showed  no  sign  of  a  fungus.  The  injured  plants  were 
on  an  exposed  hill,  where  the  winter's  winds  swept  the  ground 
bare  of  snow.  Apparently  the  roots  were  severely  injured  or 
killed  during  the  winter,  while  the  stems  were  not,  so  they  were 
able  to  leaf  out  but  not  to  develop  any  further.  The  injury  in 
some  respects  resembles  the  wilt  disease. 

RHUBARB,  Rheum  Rhaponticum. 

Stem  Rot,  Rhizoctonia  sp.  Plate  XXVIII,  b,  shows  the 
base  of  leaf  petioles  with  dark  sunken  cankers  apparently  caused 
by  the  sterile  mycelium  of  the  Rhizoctonia  fungus  which  was 


328         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

present  at  these  places.  These  specimens  were  sent  from 
Southington,  and  a  similar  trouble  was  found  on  plants  in  New 
Haven.  In  the  latter  case  the  petioles  sometimes  rotted  at  the 
base  and  the  leaves  turned  yellowish,  wilted  and  finally  died. 

SWEET  WILLIAM,  Dianthus  barbatiis. 

'R.TJST,  Puccinia  Arenariae  (Schum.)  Schrot.  Plate  XXVIII, 
c.  This  rust  was  found  for  the  first  time  in  the  state  this  year 
in  some  seedling  plants  grown  in  a  yard  in  Westville.  Only 
certain  kinds  of  the  seedlings  were  infected  and  the  trouble 
apparently  did  not  spread  to  the  others  in  the  same  bed.  This 
fungus,  like  the  hollyhock  rust,  possesses  only  the  teleuto  spores 
which  may  germinate  in  situ  as  soon  as  formed  and  thus  spread 
the  disease. 

TOBACCO,  Nicotiana  Tabacum. 

Canker  (Black  Spot*).  This  and  the  following  are  two 
warehouse  troubles  of  tobacco  not  mentioned  in  our  last  Report. 
They  appear  in  the  leaves  after  these  have  been  packed  in  cases 
for  fermentation.  Canker  is  apparently  a  fungus  trouble  in 
which  dark  colored  patches  are  produced  that  often  extend  down 
through  the  leaves  of  several  overlapping  hands.  The  injured 
tissues  are  dark  colored,  become  brittle  and  easily  fall  to  pieces. 
Microscopic  examination  reveals  the  presence  of  abundant  but 
isolated  purplish  black  spores,  apparently  those  of  Sterigmato- 
cystis  niger.  It  is  not  known  just  what  conditions  favor  the 
development  of  this  trouble,  whose  presence  is  not  known  until 
the  cases  are  opened  for  examination.  Probably  too  much 
inoisture  favors  its  development,  especially  if  care  has  not  been 
used  in  selecting  and  packing  the  tobacco. 

Must  is  a  fungus  or  bacterial  trouble  also  developed  in  the 
packed  tobacco  and  is  named  from  its  musty  odor.  Examina- 
tion of  specimens  sent  the  writer  from  East  Hartford  showed 
the  presence  of  a  slight  whitish  growth,  especially  along  the 
midribs.  Numerous  bacteria  and  also  some  molds  were  found 
in  these  growths.  Cultures  from  a  specimen  placed  in  a  damp 
chamber  produced  a  reddish  brown  mold.  Sometimes  the 
dealers  renovate  musty  tobacco  by  washing  the  leaves  with  rum. 

*  Loew,  O.  Physiological  Studies  of  Connecticut  Leaf  Tobacco.  U.  S. 
Dept.  Agr.  Rept.  65  :  48.  ' 


Alfalfa. 


PLATE  XVIII. 


a.   Leaf  Spot,  p.  311. 
Apple. 


b.    Powdery  Mildew,  p.  311.  c   Rust,  p.  312. 

FUNGI   OF  ALFALFA  AND  APPLE. 


PLATE  XIX. 


a.    I  Rust. 


b.   I  Rust.      X  2. 


c.   II  Rust.      X  2.  d.   Rust  Parasite.      X  2. 

FUNGI   OF  ASPARAGUS,  pp.  313-15. 


PLATE  XX. 


Lima  Bean. 


a.   Bacterial  Spot  of  cotyledons,  p.  316. 


b.   Brown  Rot  of  fruit,  p.  316. 
DISEASES  OF   LIMA  BEAN   AND  CHERRY. 


Dewberry, 


PLATE    XXL 

Ess  Plant. 


a.   Orange  Rust  Parasite,  p.  318. 


b.  Wilt,  p.  318. 


Fig. 


c.    Smutty  Mold,  p.  318. 
FUNGI   OF   DEWBERRY,   EGG    PLANT,   FIG. 


PLATE  XXII. 


.%s- 


:  '^^ 


a.   Showing  white  mycelium  and  minute  black  perithecia  on  leaf.      X  2. 


b.   On  the  fruit. 


c.   On  the  fiuitins;  stem. 


POWDERY   MILDEW   OF   GRAPE,  p.   319. 


PLATE  XXIII. 


Mulberiy,  p.  319. 


a.   Bacterial  disease  on  leaf. 


b.    Bacterial  disease  on  stems. 


Musk  Melon. 


c.    Bacterial  Rot  of  fruit,  p.  320. 
BACTERIAL   DISEASES  OF    MULBERRY  AND   MUSK   MELON. 


PLATE  XXIV. 


Stem  Rot  of  Onion,  p.  321. 


a.   End  view  of  rottine;  bulb. 


b.  Sclerotia  on  decayed  bulb. 


Peach,  p.  322. 


X  2. 

c.-d.   Sclerotinia  stage  of  Brown  Rot  appearing"  on  mummied  fruit. 
FUNGI   OF  ONION,   PEACH. 


PLATE  XXV. 


a.   On  the  leaf. 


b.   On  the  fruit. 


c.   On  the  twigs  producing  cankered  placesin  barl 
PEAR  SCAB,  p.   323. 


PLATE  XXVI. 


a.   Rhizoctonia  sclerotia  on  tuber. 


^:^f 


b.   Cankered  area  on  underground  stem.  c.   Corticium  stage  on  stem  just  above  ground. 

RHIZOCTONIA  FUNGUS  OF   POTATO,  p.   325. 


PLATE  XXVII. 


Bacterial  disease  of  Potato,  p.  324. 


^      *^ 


# 


a.    Diseased  root. 


b.   Cross  section  stem. 


Privet. 


c.   Winter  injury  of  California  privet  hedge,  p.  326. 
TROUBLES  OF   POTATO,   PRIVET. 


PLATE  XXVIII. 


a.    Rhizoctonia  injur}'  to  roots,  p.  326. 

Sweet  William. 


Rhubarb. 


b.   Rhizoctonia  injury,  p.  327. 


c.  Rust,  p.  32S. 
FUNGI   OF    RADISH,   RHUBARB,   SWEET  WILLIAM. 


BLIGHT    OF    MUSK    MELONS    AND    CUCUMBERS.  329 

DOWNY     MILDEW,     OR     BLIGHT,     Peronoplasmopara 

Ciihensis  (B.  &  C.)  Clint,  OF  MUSK  MELONS 

AND    CUCUMBERS. 

HISTORICAL  AND   SYSTEMATIC    CONSIDERATION. 

Early  Record.  The  downy  mildew,  or  blight,  of  cucumbers, 
musk  melons,  and  other  cucurbits  was  first  described  in  1868  by 
Berkeley  of  England  from  specimens  collected  by  Wright  on 
a  cucurbitaceous  plant  in  Cuba.  He  named  it  Peronospora 
Cubensis  B.  &  C.  The  description  given  was  very  meagre  and 
the  species  was  not  regarded  of  special  economic  importance. 
Nothing  more  was  heard  of  it  until  1889,  when  Halsted  (13) 
noted  in  the  Botanical  Gazette  that  a  serious  Peronospora 
trouble  had  been  found  on  greenhouse  cucumbers  in  New 
Jersey.  He  did  not  specifically  identify  the  fungus.  The  same 
year  Farlow  (lo),  having  seen  Halsted's  specimens,  reported 
the  fungus  as  Peronospora  Cubensis  B.  C.  and  also  stated  that 
he  had  received  specimens  on  cucumbers  and  another  cucurbi- 
tj^ceous  plant,  collected  the  previous  year  in  Japan,  sent  to  him 
by  Miyabe,  who  had  recently  examined  the  Berkeley  and  Curtis 
type  specimens  at  Kew  and  found  them  to  be  the  same.  Late 
in  this  year  Halsted  (14)  reported  that  the  fungus  had  been 
injurious  on  cucurbits  grown  outdoors  in  New  Jersey,  giving 
as  hosts  squash,  pumpkin  and  cucumbers ;  and  Galloway  (11) 
reported  it  as  a  serious  pest  of  cucumbers  in  Florida  and  Texas. 
Humphrey  (28)  reported  the  fungus  injurious  to  cucumbers 
and  squashes  in  Massachusetts  in  1890;  and  Thaxter  (61) 
found  it  the  same  year  on  cucumbers  at  South  Manchester  in 
this  state. 

Recent  Record.  Since  first  found  by  Halsted  this  ftmgus  has 
been  reported  nearly  every  year  by  some  one  in  the  United 
States  though  not  discovered  elsewhere  until  recently.  The 
fungus,  however,  has  not  been  so  common  here  in  some  years 
as  in  others,  and  seems  to  have  periods  of  vigorous  develop- 
ment for  a  year  or  two,  then  gradually  disappearing  from  con- 
spicuous view.  Apparently  in  1896  and  1897,  it  was  more  seri- 
ous than  usual,  especially  on  cucumbers,  as  it  attracted  especial 
investigation  in  these  years  from  Stewart  (53)  of  the  New 
York  and  Selby  (44)  of  the  Ohio  Experiment  Station.     Again, 


330         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

beginning  about  1901,  and  reaching  its  climax  in  1902,  it  was 
specially  destructive  in  New  England  on  musk  melons  and 
cucumbers.  In  1903  the  fungus  was  not  especially  prominent 
in  this  state,  while  in  1904  it  was  scarcely  to  be  found. 

In  1899  Massee  (36)  stated  that  the  fungus  had  recently 
been  introduced  in  England,  on  Cucurbita  pepo  and  Cucumis 
sativus,  from  Japan.  This  seems  to  have  been  its  first  appear- 
ance, or  at  least  discovery,  in  any  European  country,  though 
recently  it  has  attracted  considerable  attention  in  Russia  and 
the  Mediterranean  region.  Rostowzew  (40)  gives  an  account 
of  its  injury  (in  1902)  to  cucumbers  in  the  province  of  Twer, 
Russia,  and  the  next  year,  as  reported  by  Linhart  (35)  from 
Hungary  and  by  Hecke  (24)  from  Austria,  certain  cucumber 
and  melon  fields  of  Austro-Hungary  were  seriously  injured. 
Saccardo  (42)  and  others  also  reported  it  injurious  in  1903 
to  cucurbits  in  Italy. 

Hennings  (26)  stated  in  1902  that  the  fungus  was  collected 
in  Brazil  in  1900.  Zimmermann  (65)  also  in  1902  described 
the  fungus  as  a  new  variety  from  Java,  and  a  year  later  listed 
it  from  Dutch  East  Africa. 

Hosts  and  Distribution.  All  of  the  hosts  upon  which  this 
downy  mildew  has  been  found  belong  to  the  cucurbit  family, 
and  nearly  all  of  the  reports  of  its  occurrence  have  been  on 
the  cultivated  species.  Selby  has  reported  it  in  Ohio  on  Sicyos 
angulata  and  Echinocystis  lobata,  two  wild  species  common  in 
the  United  States,  but  he  notes  that  it  escaped  to  these  from 
a  cultivated  field  near  by.  Others  have  looked  for  the  fungus 
on  these  hosts,  but  have  not  found  it,  so  it  seems  probable  that 
they  are  not  original  hosts  in  the  United  States.  Apparently 
the  fungus  is  not  a  native  of  this  country,  but  introduced,  prob- 
ably, from  the  West  Indies,  first  in  the  southeastern  states. 
Cuba  may  have  been  its  original  home,  or  it  may  have  had  inde- 
pendent origin  in  several  places.  The  following  distribution  is 
taken  chiefly  from  the  literature  of  the  fungus,  together  with 
the  hosts  and  name  of  the  person  reporting: 

Cuctcrbitaceae:  Cuba,  type  (Berkeley),  Japan  (Farlow)  ; 
Citrullus  vulgaris,  water  melon.  Conn.  (Halsted),  N.  J.  (Hal- 
sted),  Ohio  (Selby),  Hungary  (Linhart)  ;  Cucumis  Angaria, 
gherkin  gourd,  Fla.  (Swingle),  Tex.  (Swingle)  ;  Cucumis 
Melo,    musk   melon.    Conn.    (Sturgis),    111.    (Clinton),    Mass. 


BLIGHT    OF    MUSK    MELONS    AND    CUCUMBERS.  33 1 

(Stone),  N.  H.  (Lamson),  N.  J.  (Halsted),  N.  Y.  (Stewart), 
Ohio  (Selby),  R.  I.  (Stene),  Hungary  (Linhart),  Italy  (Sac- 
cardo)  ;  Cucumis  sativus,  cucumber,  Conn.  (Thaxter),  DC. 
(Galloway),  Fla.  (Galloway),  111.  (Burrill),  Ky.  (Garman), 
Mass.  (Humphrey),  Md.  (Swingle),  Mich.  (Orton),  N.  H. 
(Lamson),  N.  Y.  (Stewart),  Ohio  (Selby),  Penn.  (Orton), 
R.  I.  (Stene),  S.  Car.  (Orton),  Tex.  (Galloway),  West  Virg. 
(Orton),  Austria  (Hecke),  Brazil  (Hennings),  Dutch  East 
Africa  (Zimmermann),  England  (Massee),  Hungary  (Lin- 
hart), Japan  (Farlow),  Russia  (Rostowzew)  ;  Cucumis  sativus 
var.  Anglicns,  English  cucumber.  Conn.  (Clinton)  ;  Cucurhita 
sps.,  squash,  Mass.  (Humphrey),  N.  J.  (Halsted),  Ohio 
(Selby)  ;  Cucurhita  moschata,  winter  crook-neck  squash,  N.  Y. 
(Stewart)  ;  Cucurhita  pepo,  pumpkin,  etc.,  N.  J.  (Halsted), 
Ohio  (Selby),  England  (Massee),  Java  (Zimmermann); 
Echinocystis  lohata,  wild  cucumber,  Ohio  (Selby)  ;  Sicyos 
angulatus,  star  cucumber,  Ohio  (Selby).  Besides  these  hosts 
Selby  of  the  Ohio  Experiment  Station  in  1899  planted  in  a 
disease  garden  a  large  number  of  cucurbits  to  determine  if  the 
fungus  would  develop  on  them.  It  spread  from  the  usual 
hosts  upon  the  following  not  reported  above:  Cucumis  odora- 
tissimus,  Cucumis  erinaceus,  Cucurhita  Melopepo,  Cucurhita 
verrucosa^?),  Lagenaria  vulgaris,  Coccinia  Indica,  Bryonopsis 
laciniosa  erythrocarpa,  Mukia  scahrella,  Momordica  halsamia, 
Momordica  Charantia,  Melothria  scahra,  Trichosanthes  colu- 
hrina. 

Systematic  Position.  Berkeley's  original  description  of  this 
fungus  is  so  vague  that  it  is  only  upon  the  authority  of  Miyabe, 
who  has  examined  the  specimens,  that  we  are  sure  of  its 
identity  with  the  specimens  since  collected.  Berkeley  placed 
it  under  the  genus  Peronospora,  calling  it  Peronospora  Cuben- 
sis  B.  &  C.  Both  Halsted  and  Tanaka  (see  Farlow  10) 
observed  the  germination  of  the  spores,  which  was  by  zoo- 
spores. Humphrey  also  reported  germination  by  zoospores,  and 
as  this  type  of  germination  is  not  characteristic  of  Peronospora, 
whose  spores  germinate  through  germ  tubes,  but  of  the  genus 
Plasmopara,  he  renamed  the  fungus  Plasmopara  Cuhensis  (B. 
&  C.)  Humph.,  but  at  the  same  time  called  attention  to  the 
fact  that  it  possessed  characters  common  to  both  genera.  A 
number  of  botanists  have  since  made  a  more  or  less  thorough 


332         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

1 

study  of  the  fungus  and  have  placed  it  under  one  or  the 
Other  of  these  genera,  sometimes  indicating  doubt  as  to  its  real 
position. 

Waite,  for  instance,  in  the  Journal  of  Mycology  in  1892, 
called  attention  to  its  resemblance  to  his  new  species,  Perono- 
spora  celtidis  and  said :  "The  conidiophores  of  P.  celtidis 
while  of  the  type  of  Peronospora  may  be  regarded  as  a  step 
toward  Plasmopara.  .  .  .  Mr.  W.  F.  Swingle  has  pointed 
out  to  me  that  Peronospora  cubensis  B.  &  C.  resembles  P.  cel- 
tidis quite  closely  and  is  its  nearest  ally  and  that  these  two 
species  form  a  group  by  themselves,  differing  considerably 
from  either  Peronospora  or  Plasmopara.  Both  have  long 
very  dark  conidia,  pointed  at  each  end  and  germinate  by  zoo- 
spores, with  conidiophores  of  the  so-called  dichotomous  type 
and  strongly  hygroscopic.  For  the  present  the  form  on  Cel- 
tis  is  thought  to  be  best  placed  in  the  genus  Peronospora." 
Swingle,  in  an  article  on  American  Peronosporaceae  in  the 
same  number  of  the  Journal,  places  these  two  species  under 
Peronospora  in  a  doubtful  section.  A  step  further  than  this 
was  taken  by  Berlese  (4)  in  1901,  when  he  created  a  new  sub- 
genus, Perono  plasma  para  Berl.,  of  the  genus  Plasmopara,  espe- 
cially for  these  two  species. 

Zimmerman  (65),  in  1902,  described  a  new  variety  of  the 
fungus  from  Java,  collected  on  leaves  of  Cucurbita  pepo,  call- 
ing it  Peronospora  cubensis  var.  atra.  This  author  labored 
under  the  impression  that  the  spores  of  P.  Cubensis  were  hyaline, 
as  has  been  stated  by  some  authors,  while  those  of  his  speci- 
mens were  a  dark  grey,  and  so  he  made  the  variety  on  this  dif- 
ference. He  also  stated  that  their  germination  in  water  was  by 
germ  tubes.  Unless  the  germination  is  always  through  germ 
tubes  there  seems  to  be  no  reason  for  considering  the  Java 
specimens  distinct   from  those  reported  elsewhere. 

Recently  Rostowzew  (40),  a  Russian  botanist,  has  studied 
the  fungus  more  in  detail  than  any  of  the  preceding  investi- 
gators and  has  decided,  like  many  of  them,  that  it  does  not 
agree  exactly  either  with  Peronospora  or  Plasmopara,  but  has 
intermediate  characters.  So  he  has  created  a  new  genus, 
Pseiidoperonospora,  for  it.  While  this  author  contrasts  and 
compares  the  type  of  this  genus  with  Peronospora  and  Plasmo- 
para,  he  makes   the   mistake  of   not  giving   a  brief   scientific 


BLIGHT    OF    MUSK    MELONS    AND    CUCUMBERS.  333 

description  of  his  new  genus,  so  that  one  is  left  somewhat  in 
doubt  as  to  just  what  its  chief  characters  are.  He  does  state, 
however,  as  have  others,  that  its  type  species  agrees  with  Pero- 
nospora  in  the  character  of  the  branching  of  the  conidiophores 
and  with  Plasmopara  in  the  conidia  having  an  apical  papilla 
and  generally  germinating  by  zoospores.  Rostowzew  also 
described  the  Russian  form  as  a  new  variety,  calling  it  Pseudo- 
peronospora  Cuhensis  var.  Tweriensis  Rostow.  He  had 
American  specimens  with  which  to  compare  his  and  found  the 
following  supposed  differences :  i  st,  The  Russian  variety 
formed  a  more  luxuriant,  felt-like,  growth  on  the  leaves ;  2d, 
the  conidiophores  were  usually  2  or  3  or  even  3  to  7  at  a 
stomate  while  the  American  specimens  had  i  or  2 ;  and  3d,  the 
conidia  averaged  slightly  larger. 

These  points,  if  fairly  constant,  would  without  doubt  entitle 
the  Russian  specimens  to  distinct  varietal  rank.  Upon  look- 
ing over  American  material,  however,  the  writer  finds  that 
there  is  considerable  variation,  and  it  seems  quite  probable  that 
Rostowzew's  specimens  from  here  did  not  show  this.  For 
instance,  on  the  water  melon  there  is  usually  no  evident  growth 
of  the  fungus ;  on  the  musk  melon  it  often  becomes  evident 
especially  at  the  juncture  of  diseased  and  healthy  tissue ;  while 
on  the  cucumber,  upon  which  host  the  Russian  variety  oc- 
curred, one  often  finds  a  very  evident  tinted  growth  on  the 
under  side  of  the  leaves,  especially  when  the  weather  condi- 
tions have  been  favorable  for  its  development.  Again,  while 
the  conidiophores  are  usually  i  or  2  at  a  stoma  in  American 
specimens,  the  writer  has  frequently  found  3  or  4  in  some  speci- 
mens, and  Stewart  (53)  of  New  York  says,  "the  number  of 
sporophores  which  proceed  from  a  single  stoma  is  small,  usually 
one  or  two ;  but  it  is  not  uncommon  to  find  as  many  as  five  and 
even  larger  numbers  are  occasionally  seen."  Finally,  the  writer 
has  measured  spores  from  the  musk  melon  that  averaged  as 
large,  or  larger,  than  the  average  and  the  large  measurements 
given  by  Rostowzew  for  his  variety.  It  seems  from  these  com- 
parisons that  the  Russian  form  is  not  distinct,  especially  since 
the   other  European   specimens  have  not  been   so   considered. 

Along  with  others  the  writer  has  had  difficulty  in  placing 
this   species  generically,  but  after   a   careful   consideration   of 


334        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

the  subject  is  in  favor  of  a  distinct  genus  for  it.  The  only 
objection  to  this  is  that  possibly  a  critical  study  of  all  of  the 
species  of  Peronospora  and  Plasmopara,  especially  as  to  their 
germination,  might  show  that  these  genera  grade  into  each  other 
through  so  many  forms  that  an  intermediate  genus  would  only 
magnify  the  difficulties  of  generic  distinctions.  Berlese's  sub- 
genus, Peronoplasmopara,  because  of  priority  of  publication 
and  also  because  it  was  given  definite  descriptive  characters, 
seems  to  merit  precedence  over  Rostowzew's  rather  indefinite 
Pseudoperonospora.  Elevating  P eronoplasmopara  to  generic 
rank,  the  distinctive  characters  of  these  three  genera,  in  the 
writer's  opinion,  are  as  follows : 

Peronospora  Cda.  Conidiophores  chiefly  of  the  dichotomous 
or  modified  dichotomous  type  of  branching;  with  branches 
spreading  mainly  at  acute  angles,  the  ultimate  spore-bearing 
tips  being  separate  and  sub-acute.  Conidia  hyaline  or  tinted, 
small  to  large,  epapillate  and  germinating  by  germ  threads. 
Haustoria  usually  conspicuous,  branched  and  filiform,  more 
rarely  abbreviated  and  simple. 

P eronoplasmopara  Berl.  Conidiophores  of  the  dichotomous 
or  modified  dichotomous  type  of  branching ;  with  branches 
spreading  mainly  at  acute  angles,  the  ultimate  spore-bearing  tips 
being  separate  and  sub-obtuse.  Conidia  chiefly  large,  tinted 
(violet  chiefly),  with  a  conspicuous  papilla  of  dehiscence  and 
germination  typically  by  zoospores.  Haustoria  small  and 
usually  simple.  Types:  P eronoplasmopara  Cubensis  (B.  &  C.) 
Clint.,  P eronoplasmopara  Celtidis  (Waite)  Clint. 

Plasmopara  Schrot.  Conidiophores  chiefly  of  the  mono- 
podial  type  of  branching,  with  the  successive  shorter  side 
branches  (and  their  sub-branches)  given  off  chiefly  at  right 
angles  to  the  main  branch,  and  with  the  ultimate,  spore-bearing 
tips  truncate  and  often  somewhat  clustered  at  the  swollen  ends. 
Conidia  chiefly  small,  hyaline,  papillate,  and  germinating  by 
zoospores.     Haustoria  small,  chiefly  ovoid. 

Specific  Description.  Since  this  species  has  been  described 
rather  meagerly  and  imperfectly,  we  give  the  following  descrip- 
tion, based  on  an  examination  of  abundant  material,  and  include 
references  to  synonymy  and  exsiccati : 


BLIGHT    OF    MUSK    MELONS    AND    CUCUMBERS.  335 

Peronoplasmopara  Cubensis  (B.  &  C.)  Clint,     n.  comb. 

Peronospora    Cubensis    B.    &    C,    Journ.    Linn.    Soc.    Bot.    10: 

363.     1868. 
Plasmopara  Cubensis  Humph.,  Ann.  Rept.  Mass.  Agr.  Exp.  Stat. 

8:   212.     1891. 
Plasmopara  {Peronoplasmopara^   Cubensis  Berl.,  Riv.  Pat.  Veg. 

9:  123.     1901. 
Peronospora  cubensis  var.  atra  Zimm.,  Centr.  Bak.  Par.  Infekt. 

8:  148.     1902. 
Pseudoperonospora  Cubensis  Rostow.,  Flora  92:    422.     1903. 
Pseudoperonospora  Cubensis  var.  Tweriensis  Rostow.,  Flora  92: 

422.     1903. 

Exsiccati :  Peronospora  Cubensis  B.  &  C,  on  Cucumis  sativus, 
S^ym.  &  Earle  Econ.  Fungi  41,  Ell.  &  Ev.  N.  A.  F.  2426  a, 
on  Cucurbita  sp.  (squash),  Ell.  &  Ev.  N.  A.  F.  2426b;  Plas- 
m,opara  Cubensis  (B.  &  C.)  Humph.,  on  Cucumis  sativus,  Syd. 
Phyc.  et  Prot.  119,  Barth.  Fungi  Col.  1840,  on  Cucumis  Melo, 
D.  Sacc.  Myc.  Ital.  1276.  ?[K.  Posch  Fungi  Par.  Exs.  Plant. 
Cult.  Hungariae.] 

At  first  forming  yellowish,  rather  indefinite  discoloration  of 
the  leaves,  but  often  finally  producing  definite  reddish  brown 
(sometimes  purplish  beneath)  dead  areas  of  varying  size  scat- 
tered over  the  leaves.  Outbreaks  of  fungus  chiefly  hypo- 
phyllous,  often  invisible  or  evident  only  at  margin  of  the  spots, 
but  sometimes  forming  a  conspicuous  purplish  growth.  Coni- 
diophores  chiefly  i  or  2,  occasionally  3  or  4,  rarely  more,  from 
a  stoma,  180  to  400;".  in  length  by  5-9 /^  in  width,  often  with 
a  slightly  swollen  base,  2-5  (chiefly  2-4)  dichotomously  (some- 
times imperfectly)  branched  from  upper  third  of  length,  with 
ultimate  spore-bearing  tips  tapering,  slightly  curved,  blunt,  and 
5-20  )u,  long  by  about  2/x  wide.  Conidia  olive  brown  to  grayish 
purple,  chiefly  ovoid  to  ellipsoidal,  with  evident  papilla  of 
dehiscence  and  sometimes  with  remains  of  pedicel  of  attach- 
ment, 2i-39ja  by  14-23/X,  though  chiefly  23-30/x,  by  i6-20/x. 
? [Oospores  spherical,  yellowish,  warty  papillate,  30-43/*,  matur- 
ing only  after  leaves  decay  in  the  ground,  according  to 
Rostowzew.] 

Hosts  and  Distr. :  on  various  Cucurbitaceae,  especially  on 
cultivated  species,  reported  from  United  States,  Cuba  (type), 
Brazil,  England,  Russia,  Austro-Hungary,  Italy,  Japan,  Java, 
Dutch  East  Africa. 


336      coxxecticut  experiment  station  report,  i9o4. 

Life  History. 

Myccliuni.  The  mycelium  consists  of  hyaline,  somewhat 
irregtilar.  branched  threads,  about  5-5-5.7 /^  iu  diameter,  that 
push  their  way  between  the  cells  of  the  leaf.  These  mycelial 
threads  are  found  more  abundantly  on  the  lower  side  in  the 
spongy  parenchyma  than  in  the  palisade,  or  closely  packed,  cells 
of  the  upper  leaf  tissues.  The  cellulose  walls  are  moderately 
thin  and  septa  are  rarely  found.  Protoplasmic  contents  at  first 
fill  the  threads,  but  later  they  may  become  empty,  especially 
in  the  old  dead  tissues.  The  threads  reach  the  surface  of  the 
leaves  usually  on  the  under  side,  pushing  their  way  through  the 
stomates  or  more  rarely  boring  directly  through  the  epidermis. 
Here  they  give  rise  to  the  conidiophores,  apparently  developing 
one  to  several  at  the  same  time,  or  subsequently,  according  to 
weather  conditions.  ^Mien  the  tissues  have  become  severely 
injured  or  killed,  the  production  of  conidiophores  gradually 
ceases  and  new  ones  are  then  formed,  chiefly  at  the  margins  of 
the  enlarging  injured  areas. 

The  mycelium  penetrates  the  cells  of  the  interior  of  the  leaf 
only  by  short  ovate  haustoria.  These  were  first  described  and 
figured  by  Humphrey  (28).  It  is  rather  difiicult  to  make  them 
out.  since  they  are  often  obscured  by  the  cell  contents.  Ros- 
towzew  found  that  they  lacked  the  cellulose  wall  of  the  mycelium 
and  that  often  they  developed  finger-like  processes  from  their 
swollen  tips.  The  object  of  the  haustoria,  of  course,  is  to  take 
food  from  the  plant  cells  for  the  growth  of  the  fung'us. 

Conidiophores.  The  conidiophores  are  the  spore-bearing 
branches  of  the  fungus,  and  from  one  to  rarely  five  or  six 
develop  from  a  single  stoma.  AA'hen  produced  abundantly  they 
make  an  evident  gTowth  on  the  exterior  of  the  leaf.  They  are 
simple  for  about  the  lower  two-thirds  of  their  length  and  dicho- 
tomously  branched  at  the  upper  third.  This  branching  is  not 
always  exactly  dichotomous,  for  sometimes  one  branch  is  larger 
and  tends  to  continue  as  the  main  stem.  The  branches  separate 
usually  at  acute  angles  and  may  be  similarly  sub-divided  several 
times,  usually  two  to  four  times.  The  main  stem  of  the  coni- 
diophere  is  5.5  to  9.5/x  wide,  with  the  base  often  slightly 
swollen  just  above  the  stomate,  and  then  it  is  sometimes  even 
ii/x.  wide  here.  The  stem  and  branches  very  gradually  narrow 
upward  so  that  the  ultimate,  conidia-bearing  tips  are  about  2/1, 


LIFE    HISTORY    OF    MELON    BLIGHT.  337 

or  less  in  width.  These  tips  or  final  branches  vary  from  5.5  to 
14/A  (rarely  longer)  in  length  and  are  usually  slightly  curved 
and  taper  somewhat  to  a  bluntish  apex.  A  single  spore  is  borne 
on  the  end  of  each  branch,  which  readily  drops  off  when  mature, 
especially  if  the  conidiophore  is  placed  in  water.  According  to 
Rostowzew,  the  ultimate  branches  end  in  temporary  sterigmatal 
tips  that  lack  cellulose  and  dissolve  in  water,  thus  freeing  the 
spores.  The  walls  of  the  conidiophores  certainly  contain  cellu- 
lose, as  shown  by  color  reaction  with  chloroiodide  of  zinc,  and 
sometimes  the  extreme  tips  fail  to  color  and  often  after  the 
spores  fall  off  are  blunt.  These  points  may  indicate  the 
fugacious  sterigmata  of  Rostowzew,  but  if  so  these  organs  are 
not  very  completely  differentiated.  The  conidiophores  vary 
greatly  in  length,  probably  depending  on  weather  conditions  at 
time  of  their  formation  or  possibly  on  the  number  produced  from 
the  same  stoma.  The  extreme  lengths  observed  were  140/x  and 
41OJU,  with  the  average  lengths  about  half  way  between  these. 
The  branching  of  the  short  conidiophore  often  begins  lower 
down  than  the  upper  third,  while  that  of  the  longer  form  may 
begin  above  this  point.  When  young  the  conidiophore  is  filled 
with  a  uniform  protoplasmic  content,  but  as  the  spores  are 
formed  this  gradually  disappears  from  the  base  upward  and  is 
all  gone  when  spore  production  ceases.  With  this  disappear- 
ance of  the  protoplasm  a  septum  or  so  is  rarely  formed  in  the 
conidiophore. 

Siiuuncr  Spores,  or  conidiospores,  or  temporary  sporangia,  as 
they  are  variously  called,  are  formed,  as  stated  above,  on  the 
tips  of  the  ultimate  branches  of  the  conidiophores.  When  small 
these  are  hyaline,  but  they  very  soon  assume  a  greyish  or  olive 
purplish  color.  When  looked  at  with  a  hand  lens  they  may 
even  appear  purple  black.  Some  authors  have  incorrectly 
described  them  as  hyaline,  and  of  course  as  seen  under  the 
high  powers  of  the  microscope  they  are  much  lighter  in  color 
than  when  seen  with  a  hand  lens,  but  even  then  they  always 
appear  strongly  tinted.  They  vary  in  shape  usually  from  ellip- 
soidal to  ovate,  but  occasionally  are  even  subspherical.  Speci- 
mens examined  by  the  writer  from  the  musk  melon  averaged 
longer  and  proportionately  narrower  than  those  from  the 
cucumber.  The  measurements  varied  from  21-39/x  in  length 
and  14-23 /x  in  width,  while  the  average  sizes  were  about  23-30/u, 


338        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I904. 

by  16-20/A.  The  spores  have  a  uniform,  rather  thin  wall,  except 
at  their  apex,  where  there  is  an  evident  hyaline  papilla  of 
dehiscence,  while  at  the  base  there  is  more  or  less  evidence  of 
the  point  of  attachment.  Except  at  these  two  points  the  cell 
wall  gives  the  cellulose  reaction  when  tested  with  chloroiodide 
of  zinc. 

Germination  of  Spores.  The  germination  of  the  spores 
through  zoospores  has  been  mentioned  by  a  number  of  writers, 
but  no  one  has  figured  or  carefully  described  this  method. 
When  placed  in  a  drop  of  water  in  a  Van  Tiegham  cell  the 
spores  sometimes  started  to  germinate  inside  of  two  to  four 
hours  if  they  were  in  good  condition.  Many  of  the  attempts  to 
germinate  the  spores  failed  altogether,  probably  because  in 
ordinary  dry  weather  the  spores  very  soon  lose  their  power  of 
germination.  Generally  they  were  successful  where  fresh 
spores,  developing  in  a  moist  atmosphere,  were  used.  In  all 
cases  the  germination  was  by  means  of  zoospores.  Occasion- 
ally a  faint  division  of  the  protoplasmic  contents  into  areas  (see 
Plate  XXXI,  5)  could  be  seen  before  the  zoospores  were  dis- 
charged, but  it  was  difficult  to  distinguish  anything  like  separate 
zoospores  even  when  apparently  completely  differentiated.  The 
zoospores  suddenly  begin  to  escape  from  the  spores  through  a 
pore  formed  by  the  dissolution  of  the  papilla  of  dehiscence. 
Usually  they  were  completely  differentiated  and  escaped  one  at 
a  time,  swimming  off  immediately  after  their  release ;  more 
rarely  they  escaped  into  a  bunch  just  outside  of  the  spore,  from 
which  they  very  soon  isolated  themselves  and  swam  away. 
The  pore  by  which  they  escape  is  too  small  to  admit  their 
unhindered  passage,  though  they  quickly  push  their  way 
through,  their  plastic  body  admitting  the  necessary  contraction 
for  this.  Plate  XXXI,  6  shows  the  dumbbell  shape  assumed  by 
a  zoospore  when  half  way  through  the  opening.  Rarely  one  of 
the  zoospores  fails  entirely  to  escape  and  may  finally  germinate 
inside  the  spore,  Plate  XXXI,  7. 

The  zoospores  very  soon  after  escape  lose  the  plasticity  of 
the  body  wall  and  assume  their  permanent  shape.  This  is 
somewhat  turtle-like ;  that  is,  oval  in  dorsal  view  (that  usually 
seen),  but  with  side  view  more  elongated,  showing  the  dorsal 
aspect  convex  and  the  ventral  often  slightly  concave.  Two 
elongated  cilia  are  attached  to  the  ventral  surface.     These  are 


LIFE    HISTORY    OF    MELON    BLIGHT.  339 

too  fine  to  be  detected  without  staining,  but  one  is  carried  for- 
ward and  the  other  extends  to  the  rear.  The  protoplasmic  con- 
tents of  the  zoospores  are  rather  uniform,  but  often  with  granules 
of  a  more  highly  refractive  index  and  with  a  prominent  vacuole 
toward  the  forward  end.  The  zoospores  swim  forward  with  a 
swift,  gliding  motion,  often  at  the  same  time  revolving  more 
slowly  around  their  elongated  axis.  At  first  they  are  very 
active,  rarely  remaining  at  rest  long  enough  for  one  to  measure 
them  accurately,  but  their  length  is  about  12  to  i8|tt.  After  an 
hour  or  two,  or  perhaps  sometimes  even  considerably  longer, 
they  become  more  sluggish  in  their  movements  and  gradually 
come  permanently  to  rest.  The  cilia  disappear  and  the  zoospore 
assumes  a  spherical  shape,  about  io-i3ju.  in  diameter  (Plate 
XXXI,  14).  Some  zoospores,  instead  of  rounding  up  entirely, 
assume  an  amoeboidal  appearance,  but  with  scarcely  any  per- 
ceptible movement,  and  eventually  go  to  pieces  without  further 
development  (Plate  XXXI,  15).  Usually  most  of  the  rounded, 
resting  zoospores  soon  begin  to  develop  germ  tubes,  into  which 
pass  their  contents.  This  germ  tube  is  the  infection  thread  by 
which  the  fungus  gains  entrance  to  its  host.  In  water  it 
becomes  a  simple  (rarely  branched)  regular  or  irregular  thread, 
eventually  several  times  the  length  of  the  resting  zoospore  from 
which  it  issues  (Plate  XXXI,  16).  After  attaining  some  length 
it  gradually  becomes  empty  of  contents  at  its  base. 

None  of  the  spores  observed  by  the  writer  germinated  directly 
through  germ  tubes,  but  always  through  zoospores.  Their 
germination,  however,  was  tried  only  in  water.  Possibly  had 
some  nutrient  solution  been  used,  the  germination  would  have 
been  by  germ  tubes,  as  the  potato  blight  spores,  which  ordinarily 
in  water  germinate  through  zoospores,  in  nutrient  solutions  will 
produce  germ  threads  instead.  Zimmermann  (65),  however,, 
describes  and  figures  the  germination  of  his  var.  atra  with 
germ  threads,  and  Rostowzew  (40)  with  his  variety  Tweriensis 
states  that  the  germination  is  either  by  germ  threads  or  zoo- 
spores. The  germ  threads  proceed  from  the  spores,  usually 
from  some  other  point  than  the  papilla  of  dehiscence.  Both 
these  authors  note  the  papilla  of  dehiscence,  and  as  this  is  char- 
acteristic of  germination  by  zoospores  this  may  be  considered 
the  typical  method. 


340         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

Infection  of  Host.  In  moist  summer  weather  the  melon  and 
cucumber  leaves  are  often  covered  with  small  drops  of  water. 
During  a  cloudy  day  these  may  remain  on  them  all  day.  This 
moisture  offers  a  means  for  the  germination  of  the  spores  pro- 
duced on  these  leaves  or  carried  there,  and  thus  an  infection  of 
the  tissues.  The  germ  tubes  of  the  resting  zoospores,  or  of 
the  spores  when  these  germinate  by  germ  threads,  bore  directly 
through  the  epidermis  or  push  their  way  between  the  guard  cells 
of  the  stomate  into  the  interior  of  the  leaf.  (See  Plate  XXXI, 
17-20.)  Infection  can  take  place  through  either  the  upper 
or  lower  surfaces  of  the  leaves.  Spores  produced  on  the 
cucumber  can  infect  leaves  of  the  musk  melon,  as  shown  by  an 
experiment  by  the  writer,  and  no  doubt  the  reverse  is  true. 
Once  inside  the  leaf  the  infection  thread  develops  the  mycelium 
and  from  this  soon  arise  the  conidiophores  to  the  exterior. 

The  extent  of  infection  depends  largely  on  weather  condi- 
tions. If  moist  for  some  time  after  the  fungus  gains  entrance 
to  its  host,  this  is  favorable  for  the  development  of  numerous 
conidiophores  and  spores  and  for  the  germination  of  the  latter. 
During  ordinary  dry  weather  the  conidiophores  are  not  produced 
very  abundantly  and  the  spores  soon  lose  their  power  to 
germinate.  The  effect  of  moisture  on  the  production  of 
conidiophores  and  spores  was  well  illustrated  in  the  infection 
experiments  carried  on  in  the  laborator3^  Usually  two  or  three 
days  after  placing  the  spores  in  water  on  the  leaves  small  dis- 
colored spots  could  be  seen  at  these  places,  showing  successful 
infection.  If  the  plants  were  then  left  exposed  to  the  ordinary 
dry  air  of  the  room,  very  few  or  no  conidiophores  were  devel- 
oped, though  the  diseased  spot  often  slowly  developed  in  the 
leaf.  But  if  the  leaves  were  sprayed  with  water  and  the  moist 
plants  covered  with  a  bell  jar  to  preserve  a  moist  atmosphere, 
there  resulted  an  evident  increase  of  conidiophores,  often  by  the 
next  day.  The  following  are  short  descriptions  of  two  of  these 
indoor  infection  experiments. 

Experiment  1769-70.  September  20  placed  spores  from 
cucumber  in  drop  of  water  on  upper  side  (1769)  of  each 
cotyledon  of  five  seedling  cucumbers  and  on  lower  side  (1770) 
of  four  seedlings;  seedlings  in  crocks  under  bell  jars.  Sep- 
tember 22,  two  cotyledons  of  1770  plainly,  and  one  faintly 
showing  small  sunken  and  discolored  spots;   bell  jars  removed. 


LIFE    HISTORY    OF    MELON    BLIGHT.  34I 

September  23,  eight  of  the  ten  cotyledons  of  1769  and  five  of 
the  eight  of  1770  showing  discolored  spots;  replaced  bell  jar 
over  those  of  1770  after  spraying  the  seedlings  with  water. 
September  29,  conidiophores  and  conidia  on  one  cotyledon  of 
1770  but  none  on  1769.  This  experiment  was  in  the  laboratory 
room,  which  was  not  adapted  for  the  plants. 

Experiment  1771-72.  September  26,  used  cucumber  seed- 
lings having  two  cotyledons  and  one  leaf  each ;  on  the  upper 
surface  (1771)  of  one  of  the  cotyledons  and  the  leaf  of  each  of 
seven  seedlings  placed  spores  from  cucumbers  in  drop  of  water 
and  on  the  upper  surface  (1772)  of  both  cotyledons  and  the 
leaf  of  seven  other  seedlings  placed  small  fragment  of  cucumber 
leaf  containing  spores ;  sprayed  plants  with  water  and  left  in 
greenhouse,  as  day  was  cloudy  and  moisture  from  leaves  did 
not  evaporate.  September  29,  only  one  or  two  leaves  of  1772 
showed  slight  discoloration.  October  i,  six  cotyledons  and  two 
leaves  of  1771  showed  slight  yellowish  discoloration  where 
spores  were  placed;  1772  showed  several  cotyledons  with  dis- 
colorations.  October  15,  1771  showed  six  of  the  seven  coty- 
ledons and  five  of  the  seven  leaves  infected,  infected  areas  dead, 
but  no  luxuriant  growth  of  conidiophores,  as  atmosphere  of 
greenhouse  was  dry;  1772  showed  every  cotyledon  and  five  of 
the  seven  leaves  infected ;  the  cotyledons  were  almost  dead  at 
this  time  and  the  dead  areas  on  the  leaves  were  more  prominent 
than  in  1771.  Conidia  and  conidiophores,  however,  were  not 
abundant,  so  sprayed  1772  with  water  and  placed  under  bell 
jar  over  night  and  the  next  morning  there  was  an  abundance  of 
new  conidiophores  developed  at  the  margin  of  the  dead  areas. 

Winter  Spores.  The  spores  that  have  been  described  so  far 
are  thin-walled,  temporary  bodies  that  cannot  survive  over  win- 
ter and  are  never  produced  saprophytically.  The  hosts,  too,  are 
annuals,  and  for  this  reason  the  mycelium  cannot  be  perpetuated 
from  year  to  year  in  perennial  parts,  as  is  the  mycelium  of  the 
potato  mildew  (blight)  in  the  tubers.  Both  these  mildews,  how- 
ever, belong  to  the  family  Peronosporaceae  and  it  is  character- 
istic of  this  family  to  produce,  besides  the  summer  spores,  large, 
thick-walled  resting  spores,  or  winter  spores,  that  are  formed 
within  the  infected  tissues  and  often  liberated  only  on  their 
decay.  Through  the  germination  of  those  spores  the  next 
season  their  hosts  are  infected  anew.  These  winter,  or 
27 


342        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

oospores,  have  been  looked  for  on  the  melon,  cucumber,  etc., 
by  a  number  of  botanists,  but  have  never  been  reported,  except 
by  Rostowzew  (40).  He  claims  to  have  found  half-matured 
oospores  in  cucumber  leaves  infected  with  this  mildew,  and  he 
gives  a  figure  and  description  of  them.  He  states  that  appar- 
ently they  do  not  'mature  until  the  leaves  have  rotted  in  the 
ground,  and  so  are  largely  saprophytic  in  their  development. 
There  is  some  question  if  what  this  writer  saw  really  had  any 
connection  with  this  fungus,  as  often  other  fungi  develop  quite 
early  in  the  dead  spots  of  the  leaves  killed  by  the  mildew.  It 
is  not  impossible  that  the  oospores  develop  only  as  a  sapro- 
phyte rather  than  as  a  parasite,  as  is  usual  with  this  stage.  There 
is  need,  however,  of  more  evidence  to  show  the  nature  and 
identity  of  the  immature  spores  Rostowzew  describes  before  they 
can  be  accepted  or  rejected  as  being  connected  with  this  mildew. 
The  writer  has  made  a  special  effort  to  discover  oospores  of  the 
fungus  on  its  recognized  hosts  in  this  state.  All  parts  of  the 
hosts,  under  all  conditions  of  infection  and  decay  and  at  differ- 
ent times  of  the  year,  have  been  examined,  but  nothing  was 
found  that  suggested  that  the  fungus  develops  such  a  stage 
either  as  a  parasite  or  a  saprophyte.  So  far  there  has  been 
obtained  no  evidence  that  the  fungus,  in  the  United  States, 
carries  itself  over  the  winter  in  this  way.  That  such  a  stage 
may  develop  under  certain  conditions*  or  in  certain  regions  or 
on  certain  hosts  is  entirely  possible.  Rostowzew  seems  to  have 
had  some  further  evidence  of  this  stage,  or  some  other  stage, 
developing  in  old  leaves  in  the  ground,  since  he  obtained  earth 
from  the  infected  region  in  Russia  and  using  this  on  beds 
planted  with  cucumbers,  finally  developed  the  disease,  while  a 
check  bed  having  none  of  this  infected  soil  on  it  did  not. 

Before  seeing  the  experiments  of  Rostowzew,  the  writer 
thought  that  possibly  the  fungus  might  be  carried  in  the  soil 
containing  the  remains  of  diseased  plants,  and  conducted  a 
couple  of  experiments  to  determine  this.  In  the  first  experi- 
ments, in  the  fall  of  1902,  dead  leaves  from  infected  vines  were 
mixed  with  new  earth  in  crocks  and  planted  with  cucumbers ; 
also  old  soil  in  which  diseased  plants  had  grown  was  placed  in 


*  It  is  barely  possible  that  the  oospores  are  produced  only  on  the 
union  of  distinct  or  sexual  mycelial  strains  that  do  not  commonly  occur 
tosrether. 


LIFE    HISTORY    OF    MELON    BLIGHT.  343 

crocks  and  planted  with  cucumbers.  These  were  kept  in  the 
greenhouse  and  the  plants  did  not  grow  very  luxuriantly,  but 
though  they  lived  two  months  no  signs  of  the  mildew  appeared. 
In  the  second  case  musk  melons  were  planted  in  a  greenhouse 
bed  in  the  winter,  and  after  they  were  up,  soil  gathered  the 
middle  of  February  from  ground  that  had  badly  diseased  melons 
in  it  the  fall  before  was  placed  around  the  plants,  which  were 
also  sprayed  with  water  drained  through  this  soil.  Other 
plants  had  the  disintegrated  remains  of  infected  leaves  placed 
on  the  soil  and  were  sprayed  with  water  drained  through  the 
leaves.  No  mildew  showed  on  these  plants  two  weeks  after 
this  treatment,  but  further  observation  was  prevented  by  sick- 
ness. These  experiments,  while  not  necessarily  contradicting 
Rostowzew's  results,  unfortunately  do  not  confirm  them. 

If,  then,  the  fungus  in  Connecticut  is  not  carried  over  the 
winter  by  summer  spores  or  mycelium,  and  if,  as  it  appears,  the 
oospores  also  are  not  developed  here,  how  does  it  manage  to  be 
perpetuated?  Two  possible  ways  have  been  suggested,  both  of 
which  may  be  of  service.  First,  it  is  quite  possible  that  the 
fungus  in  some  places  is  carried  over  winter  by  cucumbers,  etc., 
raised  in  greenhouses  and  later  in  hot-beds,  finally  spreading  to 
the  outdoor  plants  in  the  summer.  A  good  many  early  reports 
of  this  fungus  were  of  its  occurrence  upon  greenhouse  cucum- 
bers, so  that  its  occurrence  there  is  not  uncommon.  The  writer 
has  found  it  on  the  English  and  market  cucumbers  in  green- 
houses late  in  the  fall,  and  one  year  found  the  first  observed 
infection  of  the  summer  on  melons  started  originally  in  a 
greenhouse  where  cucumbers  were  usually  grown  in  the  winter. 
Second,  the  fungus  may  carry  over  winter  in  the  south  on  hosts 
that  grow  outdoors  the  year  around.  Hume  (27)  states  that 
this  is  true  in  Florida.  The  fungus  in  this  case  would  have  to 
advance  northward  with  the  season,  and  its  appearance,  no 
doubt,  would  be  greatly  influenced  by  the  character  of  the 
weather  each  year.  This  would  account  for  the  variableness 
with  which  it  appears  and  disappears.  Selby,  of  Ohio,  who  has 
been  especially  interested  in  the  study  of  this  trouble,  strongly 
supports  this  theory. 

Effect  of  Season.  As  stated  before,  the  downy  mildew 
develops  most  vigorously  when  there  is  a  very  moist  and  cold 
season,  especially  during  July  and  August.     The  cold  is  per- 


344        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I904. 

haps  not  so  favorable  for  the  development  of  the  fungus,  but 
when  the  seasons  are  unusually  moist  they  are  apt  to  be  cool  as 
a  consequence.  Periods  of  foggy  or  damp,  cloudy  weather, 
with  perhaps  not  much  rain,  offer  better  opportunities  for  the 
development  of  the  disease  than  violent  rain  storms  followed  by 
clear  weather.  Aside  from  any  injury  from  the  fungus,  a  cold, 
wet  season,  in  itself,  is  just  the  opposite  of  what  musk  melons 
need  in  this  state  for  their  best  development.  For  instance,  the 
failure  of  musk  melons  in  1903  was  as  much  due  to  the  unfavor- 
able season  for  growth  as  it  was  to  injury  by  fungi.  The  cold, 
damp  weather  retarded  the  growth  of  the  vines  so  that  they 
were  very  late  in  coming  into  bearing,  and  this,  coupled  with 
fungous  attacks,  made  the  crop  a  failure.  The  development  of 
the  cucumber  is  not  influenced  so  much  as  the  musk  melon  by 
weather  conditions. 

Injury  to  Hosts.  The  mildew  is  one  of  the  most  injurious 
pests  of  the  cucurbits.  Ordinarily  the  cucumber  and  musk 
melon  have  suffered  most,  though  the  squash  and  watermelon 
have  been  reported  as  seriously  injured.  Halsted  (17)  reported 
that  Sturgis  found  watermelons  in  this  state  severely  injured, 
but  Sturgis  made  no  statement  of  such  injury  in  the  Reports  of 
the  Station.  The  writer  has  found  the  fungus  only  a  few  times 
on  this  host,  and  then  doing  no  serious  injury.  These  speci- 
mens showed  a  few  dead  areas  on  the  leaves,  but  no  external 
evidence  of  the  fungus,  whose  presence  was  established  only 
by  microscopic  examination.  On  the  cucumber  the  fungus 
developed  much  more  aggressively.  There  was  a  greenish 
yellow  spotting  of  the  leaves  on  their  upper  surface,  while 
beneath  usually  could  be  seen  a  growth  of  the  conidiophores, 
whose  purple  black  spores  became  quite  conspicuous  under  a 
hand  lens.  Later  the  leaves  often  became  more  conspicuously 
spotted  or  withered  away,  new  growth  ceased  to  take  place  and 
the  plants  finally  died.  With  the  musk  melon  the  trouble 
seemed  to  be  most  severe,  as  the  yellowish  spots  soon  changed 
into  dead  reddish  brown  areas,  with  the  resultant  death  of  the 
intervening  tissues  and  withering  of  the  leaves.  With  weather 
favorable  for  the  spread  of  the  disease,  the  vines  very  quickly 
succumbed.  The  growth  of  the  fungus  on  the  under  side  of 
the  leaves  of  the  musk  melon  was  not  usually  so  evident  as  on 
the  cucumber  and  became  most  pronounced  at  the  border  of  the 


LIFE    HISTORY    OF    MELON    BLIGHT.  345 

dead  areas.  Even  when  the  vines  were  not  killed  outrig-ht  they 
rarely  matured  their  fruit,  or  if  some  of  the  melons  ripened  they 
always  lacked  the  requisite  flavor.     (See  Plates  XXIX,  XXX.) 

Financial  Loss.  It  is  difficult  to  estimate  the  financial  loss 
caused  by  any  disease.  In  this  state  the  injury,  due  chiefly  to 
this  fungus,  and  partially  to  other  fungi  and  unfavorable  weather 
for  growth,  was  so  great  during  the  years  1901,  1902,  1903 
that  the  area  devoted  to  musk  melons  was  gradually  cut  down 
until  it  reached  almost  a  zero  limit  in  1904,  which  year  proving 
a  fairly  favorable  season,  no  doubt  the  acreage  will  gradually 
go  back  to  the  maximum.  In  1901,  and  especially  in  1902,  the 
fungus  practically  destroyed  the  melon  fields  in  a  few  days. 

The  loss  from  injury  to  cucumbers  in  this  state,  while  possibly 
equalling  that  of  the  melons,  was  not  so  evident.  These  plants 
often  lag  along  under  the  disease  and  give  a  partial  crop,  espe- 
cially the  early  plantings,  and  the  flavor  of  the  fruit  is  not  an 
important  question.  Late  cucumbers  grown  for  pickles,  how- 
ever, suffer  worse  than  the  early,  since  the  disease  is  often  at  its 
height  when  these  are  just  starting,  and  the  vines  are  usually 
killed  before  any  fruit  is  obtained.  Raising  pickling  cucumbers 
for  the  factories  is  not  an  important  industry  in  this  state,  and 
so  the  loss  here  has  been  very  much  less  than  on  Long  Island 
and  in  Ohio. 

Conftision  with  other  Diseases.  There  are  a  number  of  other 
diseases  of  the  cucurbits  that  have  been  in  part  responsible  for 
the  injury  of  these  hosts.  It  is  not  always  possible  for  one  not 
well  acquainted  with  these  to  distinguish  them  from  the  downy 
mildew.  With  this  the  most  distinguishing  macroscopic  char- 
acter is  the  growth  of  the  fungus  on  the  under  surface  of  the 
spots,  especially  at  the  margins,  the  purplish  black  spores  on  the 
conidiophores  becoming  quite  evident  when  a  hand  lens  is  used. 
The  distinguishing  characters  of  the  other  troubles  as  deter- 
mined by  the  naked  eye  or  a  hand  lens  are  as  follows : 

Scab,  Cladosporium  cucumerinum,  occurs  on  the  leaves,  stems 
and  fruit,  producing  sunken  areas  on  the  latter  two,  and  the 
dead  spots  become  covered  with  a  more  or  less  evident  olive, 
moldy  fungous  growth. 

Leaf  Spot,  Alternaria  Brassicae  var.  nigrescens,  usually  forms 
roundish,  dead,  reddish  brown  spots  on  the  leaves ;  these  spots 
often  show  faint  concentric  rings  of  development,  but  no  evi- 


346         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

dent  fungous  growth.  This  sometimes  becomes  a  serious 
trouble,  considerably  resembling  the  downy  mildew  in  its 
ultimate  effect  and  appearance. 

Anthracnose,  Colletotrichnm  Lagenarium,  is  a  common  and 
widespread  trouble  present  more  or  less  each  season.  It  is  most 
conspicuous  on  the  ripening  fruit,  but  this  is  often  attacked 
while  quite  green,  showing  sunken,  rotten  areas  that  are  usually 
covered  with  pinkish,  often  sticky,  exudations  of  spores.  The 
minute  spore  exudations  on  the  leaves  are  easily  washed  off  by 
rain,  and  the  reddish  brown  spots  are  very  similar  to  those  of 
the  leaf  spot,  but  angular  and  often  more  extended. 

Bacterial  Wilt,  Bacillus  tracheiphilus  Sm.,  often  wilts  down 
the  whole  vine  without  any  spotting  of  the  leaves,  which  merely 
dry  up  on  their  petioles.  Sometimes,  however,  there  appear 
distinct,  often  semi-pellucid,  areas  in  the  leaves.  In  the  former 
case  the  bacteria  merely  clog  the  water  ducts  and  cut  off  the 
supply  of  water  from  the  leaves,  which  then  wither  and  die, 
while  in  the  latter  case  the  bacteria  also  cause  disease  of  the 
leaf  tissues.  A  soft  bacterial  rot  of  the  fruit,  apparently,  is 
sometimes  connected  with  this  trouble. 

Prevention. 

Cucumber.  So  destructive  has  the  downy  mildew  proved  to 
cucumbers  grown  in  the  eastern  United  States  that  a  number 
of  experiment  stations  have  made  experiments  to  determine  if 
it  could  be  controlled.  Practically  all  of  the  experimental  work 
has  been  done  by  spraying  with  Bordeaux  mixture,  the  chief 
points  of  interest  being  to  determine  if  the  disease  could  be  con- 
trolled, when  and  how  often  it  was  necessary  to  spray,  and  if 
spraying  could  be  done  on  a  paying  basis. 

Halsted  (20)  of  New  Jersey  was  the  first  to  report  spraying 
experiments  against  this  trouble,  conducted  in  1895.  He  wrote 
in  part  as  follows :  "Spraying  with  Bordeaux  gave  very  favor- 
able results  in  the  cucumber  belts  so  treated.  Two  fungi 
peculiar  to  the  cucumber,  namely,  the  mildew  (Plasmopara 
Cubensis  B.  &  C.)  and  anthracnose  {Collet otrichum  Lagena- 
rium Pass.),  were  sufficiently  abundant  to  do  serious  injury. 
.  .  .  By  August  20  the  combined  attack  of  fungi  and  insects 
resulted  in  the  destruction  of  most  of  the  vines  in  all  of  the  belts 


PREVENTION    OF    MELON    BLIGHT.  34/ 

except  in  the  two  sprayed  with  Bordeaux.  ...  As  a  result 
the  Bordeaux  vines  were  green  and  vigorous  for  over  a  month 
after  those  in  the  adjoining  belts  were  dead.  The  yield  of 
fruits  was  considerably  increased  and  the  percentage  of  fruit- 
rot  greatly  diminished." 

The  next  year  Stewart  (53)  of  New  York  carried  on  experi- 
ments on  Long  Island  to  prevent  this  trouble  on  late  or  pickling 
cucumbers,  which  were  being  severely  injured  in  that  region. 
He  says  in  his  report  of  these  experiments  :  "The  downy  mildew 
first  appeared  on  the  unsprayed  plants  August  7,  and  by  August 
21  it  had  injured  the  foliage  to  such  an  extent  that  scarcely  any 
cucumbers  were  produced  after  this  date.  The  thirty-two  rows 
of  plants  which  had  been  sprayed  were  in  perfect  health  and 
vigor  on  August  21,  and  after  this  date  produced  two  hundred 
and  sixty  dollars  worth  of  cucumbers,  which  represents  approxi- 
mately the  benefit  resulting  from  spraying."  In  1897  and  in 
1898  Stewart  and  Sirrine  carried  on  other  successful  spraying 
experiments,  both  with  early  and  late  cucumbers.  These  experi- 
ments were  conducted  on  a  large  scale  and  gave  satisfactory 
financial  results. 

Selby  (44)  of  Ohio,  in  1897,  also  conducted  successful  spray- 
ing experiments  on  late  or  pickling  cucumbers.  He  makes  the 
following  statement:  "For  Wayne  County,  Ohio,  this  fungus 
disease  has  caused  in  1897  a  loss  of  about  GGYs  per  cent,  of  the 
crop.  Computed  at  an  average  of  about  210  bushels  per  acre, 
and  one-third  large  pickles,  this  loss  at  factory  prices  reaches 
almost  $45,000  for  the  single  season  in  Wayne  County.  .  .  . 
These  two  diseases  (mildew  and  anthracnose)  may  be  very 
largely,  if  not  entirely,  suppressed  by  spraying  about  seven  times 
with  Bordeaux  mixture,  making  the  first  application  as  the 
plants  begin  to  vine  and  keeping  the  leaves  covered  with  the 
fungicide  thereafter,  until  about  September  10.  The  cost  for 
these  sprayings  need  not  exceed  $10  per  acre,  and  may  be 
reduced  to  $7.50." 

Since  these  earlier  and  most  extensive  experiments  several 
other  investigators  have  reported  more  or  less  successful  experi- 
ments. With  those  conducted  by  the  writer,  chiefly  against  the 
mildew  on  the  musk  melon,  one  row  of  cucumbers  was  also 
sprayed,  and  the  results  obtained  in  this  case  were  sufficient  to 
show  that  ordinarily  the  mildew,  anthracnose,  leaf  spot  and  scab 


348        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I904. 

could  be  controlled  on  this  host  by  spraying  a  sufficient  number 
of  times  with  Bordeaux,  and  that  when  these  troubles  were  bad 
such  treatment  was  a  paying  venture.  The  bacterial  wilt,  how- 
ever, seemed  to  be  as  bad  on  the  sprayed  as  on  the  unsprayed 
vines. 

The  consensus  of  opinion,  then,  seems  to  be  favorable  for 
spraying  cucumbers,  especially  late  cucumbers  raised  for 
pickling,  when  suffering  from  mildew,  anthracnose,  etc.  Of 
course,  in  the  years  when  these  fungous  troubles  are  not 
injurious  spraying  would  not  pay  for  itself.  Bordeaux  mixture 
(four  pounds  copper  sulphate,  four  pounds  lime  and  forty  to 
forty-five  gallons  water)  is  the  best  fungicide  for  this  purpose. 
The  spraying  should  begin  about  July  5  to  15,  according  to  the 
season,  but  the  first  application  should  always  precede  rather 
than  follow  the  first  appearance  of  the  disease.  From  five  to 
seven  sprayings  are  necessary  to  keep  the  foliage  well  covered 
with  the  fungicide  until  the  first  part  of  September.  Where  an 
acre  or  less  of  cucumbers  are  grown  the  small  barrel  pump 
mounted  on  two  wheels  and  dragged  by  hand  is  a  very  con- 
venient outfit.  The  vines  can  be  trained  about  every  fifty  feet 
so  that  a  path  of  sufficient  width  for  the  cart  can  be  kept  open. 
From  this  the  vines  on  each  side  can  be  sprayed  by  using  a 
twenty-foot  hose,  one  man  pumping  and  pulling  the  cart  and 
another  spraying  the  vines.  Where  more  than  an  acre  of 
cucumbers  are  grown  it  is  advisable  to  leave  roadways  (perhaps 
planted  with  some  early  maturing  crop),  and  from  these  the 
vines  can  be  sprayed  from  a  barrel  pump  carried  in  a  light 
wagon.  Before  each  spraying  the  ripe  cucumbers  should  be 
picked,  otherwise  no  attention  need  be  paid  about  the  spray 
getting  on  the  fruit. 

Musk  melons:  experiments  elsewhere.  The  spraying  experi- 
ments against  this  trouble  on  the  musk  melon  are  not  nearly  so 
favorable  as  those  on  the  cucumber.  In  fact,  when  the  mildew 
is  severe  it  is  doubtful  if  any  good  results,  and  even  taken  year 
in  and  year  out  very  little  will  be  gained  if  the  failures  are 
counted  in.  This  does  not  mean  that  good  does  not  result  some- 
times from  spraying,  as  regards  moderate  attacks  and  especially 
with  anthracnose,  leaf  spot  or  scab,  which  are  more  easily  con- 
trolled, but  in  general  the  results  do  not  warrant  the  extra  cost 
and  trouble  of  spraying. 


PREVENTION    OF    MELON    BLIGHT.  349 

Selby  (46)  of  Ohio  was  one  of  the  first  to  report  spraying 
experiments,  made  in  1898,  against  the  mildew  on  musk  melons. 
His  experiments  were  not  so  extensive  with  the  musk  melon 
as  with  the  cucumber,  and  while  favorable  results  were  reported 
in  one  case,  he  states :  "On  the  whole,  we  cannot  conclude  that 
the  use  of  Bordeaux  mixture  for  the  fungus  parasites  of  the 
musk  melon  has  proven  a  decided  success." 

Lamson  (33)  reports  that  spraying  experiments  in  1901  made 
on  garden  musk  melons  after  the  mildew  appeared  gave  little, 
if  any,  good  results,  while  in  1902  (34)  treatments  started 
earlier  and  repeated  five  times  kept  the  musk  melons  alive  two 
or  three  weeks  later  than  those  not  sprayed. 

Stone  and  Smith,  in  the  15th  Ann.  Rept.  of  Mass.,  write  as 
follows:  "The  subject  of  spraying  as  a  preventive  for  this 
trouble  has  received  considerable  attention  from  this  division 
for  several  years.  During  the  past  season  [1902]  experiments 
were  made  in  cooperation  with  a  local  grower  along  the  lines 
which  previous  experience  had  suggested.  The  details  of  this 
work  will  be  reserved  for  a  bulletin ;  but  it  may  be  said  here 
that,  even  where  plants  were  thoroughly  sprayed  with  Bordeaux 
mixture,  commencing  early  in  July  when  the  first  leaves  devel- 
oped, no  effect  could  be  seen  upon  the  development  of  the 
mildew,  sprayed  and  unsprayed  plots  and  fields  were  alike  a 
complete  failure." 

Bennett  (i)  of  Storrs  Station,  this  state,  reports  spraying 
experiments  in  1903,  as  follows :  "Three  plots  of  musk  melons 
were  planted,  two  of  which  were  sprayed,  the  third  being  left 
unsprayed.  Owing  to  the  cold  season  none  of  the  melons 
matured  fruits.  The  result  of  the  spraying  was  practically  the 
same  with  the  melons  as  with  the  cucumbers.  Traces  of  blight 
could  be  seen  on  the  sprayed  foliage,  but  they  were  not  suf- 
ficiently abundant  to  do  any  harm.  The  unsprayed  plants 
succumbed  to  the  disease  even  before  the  cucumbers  did." 

Musk  melons:  experiments  in  Connecticut.  During  the  three 
seasons  1902,  1903,  1904,  the  writer  conducted  a  number  of 
experiments  to  determine  how  efficient  and  practical  spraying 
was  in  preventing  the  downy  mildew  and  other  fungous  troubles 
of  the  musk  melon.  Each  year  presented  weather  conditions 
somewhat  different,  varying  from  exceedingly  favorable  to 
unfavorable   for  the  development  of  the  mildew.      From  the 


350        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I904. 

results  of  these  experiments,  coupled  with  the  experience  of 
others,  we  have  come  to  the  conclusion  that  spraying  musk 
melons  with  Bordeaux  as  a  yearly  practice  will  give  no  better 
average  financial  results  than  where  no  spraying  is  practiced. 
There  are  probably  seasons  when  spraying  would  pay,  if  these 
could  be  foretold,  but  again  there  are  seasons  when  it  will  be 
money  thrown  away.  The  results  of  these  experiments  are  as 
follows : 

In  ig02  the  mildew,  which  evidently  had  been  very  injurious 
to  musk  melons  the  year  before,  was  first  found  in  New  Haven 
in  a  private  garden  about  the  middle  of  July.  From  then  on  to 
the  first  of  August  it  appeared  on  practically  all  of  the  cucum- 
bers and  musk  melons  raised  in  this  vicinity.  With  the  musk 
melons  the  injury  was  sudden  and  severe,  so  that  all  of  the 
vines  were  dead  before  any  fruit  ripened  thoroughly.  This  was 
a  cold,  wet  year,  especially  in  July,  which  was  unusually  cold 
and  foggy. 

1.  July  19  the  writer  examined  three  small  patches  of  musk 
melons  in  the  garden  of  Mr.  Sperry,  New  Haven,  and  found 
the  first  outbreak  of  the  mildew  observed  this  year.  The  plants 
of  the  oldest  patch  had  been  started  in  the  greenhouses,  to  mature 
them  earlier,  and  these  showed  the  disease  rather  badly,  while 
the  two  younger  patches  were  not  yet  visibly  infected.  Upon 
the  advice  of  the  writer,  the  gardener  sprayed  these  younger 
vines  a  few  days  later.  August  2  visited  the  garden  again 
and  found  this  spraying  had  not  prevented  the  appearance  of 
the  disease  on  these  melons,  which  were  now  in  about  the  con- 
dition of  the  older  melons  when  first  seen.  Numerous  rains, 
however,  had  washed  off  all  the  spray.  The  vines  soon  died, 
with  no  melons  matured. 

2.  M.  W.  Frisbie  &  Son,  of  Southington,  on  July  28,  sprayed 
part  of  their  commercial  field  at  the  writer's  suggestion.  At 
this  time  no  mildew  was  seen  in  the  field,  though  some  bacterial 
wilt  was  present.  When  examined  again,  August  8,  a  few 
leaves  showed  the  presence  of  the  mildew.  It  was  intended  by 
the  writer  that  other  sprayings  should  be  given,  but  wet  weather 
prevented  at  the  proper  time,  and  then  the  owners  were  afraid 
the  spray  might  injure  the  appearance  of  the  fruit.  No  good 
resulted  from  this  single  treatment  and  the  crop  was  a  failure. 

3.  August  4  the  writer  sprayed  a  row  of  melons  in  each  of 
two  fields  on  the  farm  of  Mr,  Nesbit  in  Hamden.     At  this  time 


PREVENTION    OF    MELON    BLIGHT.  351 

the  mildew  was  just  beginning  to  appear  scattered  through  the 
fields,  though  a  week  previous  the  anthracnose  and  bacterial  wilt 
had  been  noticed  in  spots.  August  9  examined  the  field  and 
found  the  mildew  spreading  rapidly,  with  little  difference 
between  sprayed  and  unsprayed  plants.  August  13  one  of  these 
fields  was  pulled  up,  as  both  sprayed  and  unsprayed  plants  were 
beyond  recovery.  Sprayed  the  second  field  again  on  this  date, 
but  expected  little  or  no  good  to  result,  as  plants  were  severely 
injured.  This  field  also  was  soon  pulled  up,  as  no  melons  were 
expected  from  either  sprayed  or  unsprayed  plants. 

4.  August  5,  a  little  mildew  was  first  seen  on  a  few  melons 
grown  on  the  Experiment  Station  grounds,  and  on  August  7 
a  part  of  these  were  very  thoroughly  sprayed  with  Bordeaux 
mixture.  A  few  vines  were  sprayed  above  and  then  turned 
over  and  sprayed  on  their  under  surface.  On  August  20  the 
vines  were  sprayed  thoroughly  again.  The  mildew  carried  off 
the  unsprayed  vines  finally.  Those  thoroughly  sprayed  on  both 
surfaces  did  not  develop  the  mildew  much  further,  but  they 
failed  to  make  sufficient  new  growth  to  mature  their  fruit. 
Plate  XXX,  b,  shows  the  condition  of  sprayed  and  unsprayed 
vines  on  August  30. 

5.  August  23,  sprayed  the  greater  part  of  a  small  patch  of 
musk  melons  in  the  garden  of  Mr.  Hartley  at  Centreville.  The 
blight  had  rather  severely  injured  these,  but  the  spraying  was 
made  to  see  if  its  advance  could  be  checked  and  the  melons 
recover  by  new  growth.  September  2,  examined  the  patch 
again,  but  as  no  beneficial  results  of  the  spraying  could  be  seen 
no  further  treatments  were  given.     No  melons  matured. 

It  will  be  noticed  that  most  of  these  experiments  were  started 
after  the  appearance  of  the  mildew  on  the  vines.  This  was 
because  the  writer  did  not  take  up  his  work  at  the  Station  until 
July  and  so  did  not  know  what  to  expect  from  this  trouble.  It 
was  thought  desirable,  however,  to  make  these  tardy  treatments 
to  see  if  the  disease  could  be  checked  and  a  partial  crop  obtained. 
The  experiments  show  that  this  certainly  cannot  be  done  when 
the  disease  is  at  all  serious  and  the  season  unfavorable  for  the 
growth  of  the  vines.  However,  it  is  quite  certain  that  very  few 
or  no  melons  would  have  been  obtained  even  had  the  spraying 
■  been  started  early  and  applied  thoroughly  through  the  season,  as 
the  following  reports  from  Connecticut  growers  for  this  year 
show : 


352         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

6.  Mr.  J.  C.  Eddy  of  Simsbury  sprayed  melons  five  times, 
twice  in  the  greenhouse  before  transplanting.  These  vines  were 
somewhat  better  than  those  not  sprayed,  but  still  "blighted" 
and  produced  no  marketable  fruit. 

7.  Mr.  J.  S.  Eddy  of  Unionville  thoroughly  sprayed  his 
melons,  but  they  did  not  amount  to  anything.  When  examined 
by  the  writer  on  August  26  no  mildew  was  found,  but  there  was 
a  small  amount  of  leaf  spot.  The  cold,  damp  season,  appar- 
ently, was  chiefly  responsible  for  their  feeble  growth,  which  the 
owner  described  as   "hide  bound."     The  crop  was  a  failure. 

8.  Mr.  C.  B.  Meeker  of  Westport  sprayed  his  melons  six  or 
seven  times,  beginning  as  soon  as  the  vines  started  to  run.  He 
got  no  results  from  his  spraying. 

9.  Mr.  E.  M.  Ives  of  Meriden  sprayed  a  few  melons  in  his 
garden.  He  sprayed  both  sides  of  the  leaves,  turning  the  vines 
over  to  reach  the  under  surface.  He  reports  a  few  melons  for 
his  trouble. 

In  ipo^  the  growing  season  was  also  wet  and  somewhat  cool, 
but  not  so  bad  as  the  previous  one.  The  mildew  was  very  much 
later  in  its  appearance,  being  first  found  in  the  vicinity  of  New 
Haven  September  14.  On  the  whole  it  did  no  more  damage  to 
musk  melons  than  did  anthracnose,  leaf  spot,  scab  or  wilt,  all 
of  which  were  found  during  the  season,  sometimes  several 
occurring  together  in  the  same  field.  Taken  altogether,  these 
various  fungus  pests  perhaps  did  not  do  as  much  injury  to  the 
melons  as  the  cold,  wet  growing  season  did  in  preventing  favor- 
able growth  of  the  vines.  Little  or  no  fruit  was  gathered  from 
any  of  the  fields  and  gardens. 

10.  A  spraying  experiment  this  year  was  made  at  the 
Experiment  Station  grounds  on  musk  melons  especially  planted 
for  this  purpose  and  carefully  watched  during  the  whole  season. 
A  row  each  of  Early  Gem,  Jenny  Lind  and  Hackensack  (also 
one  of  cucumbers)  was  planted  and  divided  into  five  equal 
plats.  These,  except  the  fifth,  or  check  plat,  were  all  sprayed 
five  times,  as  follows :  July  14,  July  28,  August  8,  August  26, 
September  10.  The  season  was  late,  so  that  the  first  spraying 
was  made  on  the  plants  when  quite  small  and  with  no  sign  of 
any  fungous  disease  on  them.  Bordeaux  mixture  was  used  on 
all  four  plats  for  the  first  three  treatments,  after  which  plat  i 
received  two  treatments  with  resin  Bordeaux,  plat  2  two  treat- 


PREVENTION    OF    MELON    BLIGHT.  353 

ments  with  soda  Bordeaux,  plat  3  two  treatments  with  potas- 
sium sulphide,  and  plat  4  two  treatments  with  fresno  (ammo, 
sol.  cop.  carb.).  These  other  fungicides,  except  resin  Bor- 
deaux, were  used  in  the  last  two  sprayings  to  avoid  any  sediment 
on  the  fruit  when  ripe,  as  some  growers  seem  to  be  afraid  to 
spray  after  the  melons  begin  to  ripen. 

The  conclusions  drawn  from  this  experiment  are  as  follows : 
(a)  The  sprayed  plats,  especially  the  Bordeaux  plat  i,  gave 
the  best  results  in  freedom  of  the  foliage  from  fungi  and  in  size 
and  vigor  of  plants  and  number  of  young  melons  started.  The 
unsprayed  plat  5  was  the  poorest  in  these  respects  and 
developed  considerable  anthracnose  and  scab,  and  possibly  a 
little  mildew  at  the  very  end  of  the  season,  (b)  The  spraying 
did  no  good  in  preventing  the  bacterial  wilt,  as  a  few  plants 
were  killed  in  all  of  the  plats  and  the  fruit  suffered  some  from 
a  soft  rot,  possibly  caused  by  the  same  organism.  Some  of 
the  earlier  sprayings  did  some  slight  injury  to  the  leaves,  shown 
by  their  turning  yellow  at  the  margins  and  slowly  dying, 
(d)  Resin  Bordeaux  adheres  better  than  Bordeaux,  but  is  more 
expensive  and  difficult  to  make,  and  so  will  not  generally  be 
used.  If  any  spraying  is  to  be  done,  everything  considered, 
Bordeaux  mixture  is  the  most  desirable  fungicide,  even  for  the 
late  sprayings,  as  little  spray  reaches  the  melons  if  the  ripe 
ones  are  picked  before  spraying,  and  no  injury  or  harm  can  come 
from  any  little  sediment  that  may  remain  when  the  fruit  is 
picked  subsequently,  (e)  The  spraying  in  this  experiment  did 
not  pay  for  itself,  since  practically  no  marketable  melons  were 
obtained.  The  failure  of  melons  on  the  sprayed  vines  was 
chiefly  due  to  the  cold,  wet  season,  which  prevented  vigorous 
growth  of  foliage. 

In  ip04  the  season  was  warm  and  fairly  dry  during  July  and 
August,  so  that  it  was  favorable  for  the  growth  of  the  vines, 
and  also  unfavorable  for  the  development  of  fungous  troubles. 
No  mildew  was  found  by  the  writer  anywhere,  except  a  little 
on  some  garden  cucumbers  on  September  lo.  So  this  fungus 
did  no  damage  whatever  this  season ;  neither  were  the  other 
fungous  diseases  troublesome,  so  far  as  observed,  except  the 
wilt,  which  did  less  damage  than  usual.  For  the  first  time  in 
several  years,  due  chiefly  to  the  warmer,  drier  growing  season, 
a  fair  crop  of  musk  melons  was  generally  obtained  throughout 


354         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

the  state,  though  this  was  shortened  somewhat  by  a  kilHng  frost 
on  September  21. 

II.  A  spraying  experiment  this  year  was  conducted  on  the 
farm  of  Andrew  Ure  of  Highwood  to  determine  whether  spray- 
ing with  Bordeaux  mixture  was  a  desirable  and  profitable 
treatment  to  advocate  to  market  gardeners  for  their  melons.  A 
patch  of  about  a  quarter  of  an  acre  was  planted  by  Mr.  Ure  for 
this  purpose  and  two-thirds  of  this  was  thoroughly  sprayed  four 
times.  These  treatments  were  made  July  6,  July  21,  August  4 
and  August  18,  and  as  the  season  was  not  very  wet  the  vines 
were  fairly  well  coated  with  the  spray  during  the  entire  season. 

The  results  may  be  summarized  as  follows:  (a)  No  mildew 
appeared  on  either  sprayed  or  unsprayed  plants.  A  little  leaf 
spot  was  finally  observed  on  some  of  the  unsprayed  plants,  but 
there  was  not  enough  to  do  any  damage.  The  bacterial  wilt 
injured  and  killed  a  few  vines  and  there  was  considerable  injury 
from  a  soft  bacterial  rot  of  the  fruit  about  the  time  of  its 
maturity,  probably  also  caused  by  the  wilt  organism.  (See 
Plate  XXIII,  c.)  As  shown  last  season  and  in  this  experiment, 
spraying  was  of  little  or  no  benefit  in  preventing  the  wilt, 
(b)  Th^  first  spraying  was  really  made  on  all  of  the  vines, 
except  two  rows,  but  as  it  looked  as  if  the  treatment  had  caused 
some  yellowing  of  the  foliage,  over  one-third  of  the  patch  was 
left  unsprayed  thereafter.  No  evident  or  permanent  injury 
resulted  from  spraying,  however.  At  the  end  of  the  season  the 
sprayed  vines  looked  fully  as  vigorous,  if  not  a  little  more  so, 
than  those  which  were  not  sprayed.  The  spraying,  then,  was 
of  little  or  no  benefit  to  the  foliage  and  vines,  (c)  A  fair  crop 
of  melons  was  gathered  from  both  sprayed  and  unsprayed  vines. 
No  effort  was  made  to  determine  the  exact  number  from  each, 
as  it  was  evident  that  if  any  difference  existed  (and  it  would 
have  been  small)  it  would  scarcely  be  due  to  the  spraying. 

CONCLUSIONS  FROM  EXPERIMENTS.  Summing  up  the 
results  of  these  three  seasons'  experiments,  ■we  conclude :  First — 
When  the  dovyny  mildew  is  very  severe,  as  in  1902,  spraying  musk 
melons  is  useless.  Second — When  the  seasons  are  cold  and  damp  but 
fungi  not  unusually  destructive,  spraying  may  show  some  benefit  to  the 
foliage,  but  the  unfavorable  influence  of  the  weather  will  not  be  over- 
come by  this  treatment.  Third — Warm,  fairly  dry  seasons  (moisture 
well  distributed)  are  necessary  for  the  best  development  of  musk  melons 
■in  Connecticut  and  such  seasons  are  not  likely  to  bring  serious  attacks 


LITERATURE   ON    MELON    BLIGHT.  355 

of  fungi,  so  that  spraying  in  these  seasons  is  of  little  or  no  advantage. 
Fourth — Everything  considered,  spraying  musk  melons  scarcely  merits 
recommendation  in  this  state.  These  statements  do  not  apply  to  the 
cucumber,  which  host  vvithout  doubt  is  often  benefited  by  thorough 
spraying. 

Literature. 

The  following  references  include  all  the  more  important 
articles  and  even  notes  which  the  writer  has  found  in  literature 
relating  to  this  mildew.  As  a  natural  consequence  of  the 
fungus  being  found,  until  recently,  chiefly  in  this  country,  and 
because  of  its  severe  injury  to  cultivated  plants,  the  literature  is 
largely  from  our  Experiment  Station  workers. 

1.  Bennett,  E.  R.     Bordeaux  Spraying  for  Melon  Blight.     Storrs  Agr. 

Exp.  Stat.  Bull.  30:17.     1904. 

Reports  favorable  results  from  spraying  seven  times  with  Bor- 
deaux mixture,  especially  vi^ith  the  yield  and  foliage  of  the  cucum- 
bers, while  with  musk  melons  the  foliage  was  improved. 

2.  Berkeley    and    Curtis.     Peronospora    Cubensis    B.    &    C.     Journ. 

Linn.  Soc.  Bot.  10 :  363.     1868. 

Describe  this  new  species  collected  on  cucurbitaceous  host  by 
Wright  in  Cuba. 

3.  Berlese,  A.  N.  and  De  Toni,  J.  B.     Peronospora  cubensis  Berk,  et 

Curt.     Sacc.  Syll.  Fung.  7:261.     1888. 
Give  Berkeley's  description  of  this  fungus. 

4.  Berlese,   A.   N.     Plasmopara   cubensis    (B.   et  C).     Riv.    Pat.   Veg. 

9 :  123-6.     1901.     [Illustr.] 

Gives  botanical  description,  hosts,  distribution  and  general  dis- 
cussion of  this  fungus,  for  which  he  creates  a  new  sub-genus, 
Peronoplasmopara. 

5.  Cazzani,   E.     Sulla   comparsa   della  Peronospora  cubensis   Berk,  et 

Curt,  in  Italia.     Centr.  Bakt.  Par.  Infekt.  12 :  744.     1904.     [Reprint 
from  Atti  Inst.  Bot.  Pavia  9 :  14.     1903-4.] 

Reports  this  on  melon  leaves  from  Pavia  and  Rimini,  Italy, 
in  1903. 

6.  Clinton,  G.  P.     Report  on  Fungous  Diseases  of  1903.     Conn.  Pom. 

Soc,  Ann.  Vol.  6  :  23.     1904. 

States  that  downy  mildew  appeared  later  and  did  less  damage 
in  Conn,  in  1903  than  it  did  the  previous  year. 

7.  Clinton,  G.  P.     Downy  Mildew   (Blight)  Plasmopara  Cubensis   (B. 

&  C.)  Humph.     Conn.  Agr.  Exp.  Stat.  Rept.  1903:318-19,  330-31, 
370.     1904.     [Illustr.] 

Gives  a  short  account  of  the  fungus,  with  its  hosts  and  the 
injury  done  in  Conn. 

8.  Cooke,  M.  C.     Cucumber  and  Melon  Rot  Mould.     Journ.  Roy.  Hort. 

Soc.  27  :  823.     1903. 


35^        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I904. 

Gives    short    note    on    this    fungus    with    suggestions    for    its 
prevention. 
9.  Eckardt,  C.  H.     Ueber  die  wichtigsten  in  neuerer  Zeit  aufgetretenen 
Krankheiten  der  Gurken.     Prakt.  Blat  Pflanzenb.  Pflanzensch.  2 : 
[Revievi?  by  Posch,  Centr.  Bakt.  Par.  Infek.  13 :  787.     1904.] 

Notes  injury  in  Austria  from  this  trouble,  and  suggests  spraying. 
ID.  Farlow,  W.  G.     Notes  on  Fungi  I.     Bot.  Gaz.  14 :  189-90.     1889. 

Gives  a  general  account  of  Peronospora  Cubensis  received  from 
Japan,  and  identifies  specimens  from  Halsted  of  New  Jersey, 
the  latter  being  the  first  collection  in  the  United  States. 

11.  Galloway,   B.  T.     New  Localities   for  Peronospora  Cubensis  B.  & 

C.     Journ.  Myc.  5 :  216.     1889. 

Reports  this  from  Fla.  and  Texas,  on  cucumbers,  which  suffer 
severely  from  the  fungus. 

12.  Garman,  H.     Cucumber  Mildew.     Ky.  Agr.  Exp.  Stat.  Bull.  91:  50-1. 

1901. 

Notes  this  fungus  especially  destructive  to  cucumbers  in  Ken- 
tucky in  1897  and  1898 ;  finds  conidia  larger  than  described  by 
Berkeley. 

13.  Halsted,  B.  D.     Peronospora  upon  cucumbers.     Bot.  Gaz.  14 :  152-3. 

1889. 

Notes  appearance  of  an  unidentified  Peronospora  (see  Farlow) 
on  greenhouse  cucumbers  in  May,  1889,  at  New  Brunswick,  N.  J. 
This  is  the  first  collection  of  the  mildew  in  the  United  States. 

14.  Halsted,    B.    D.     Some    Notes    upon   Economic    Peronosporeae    for 

1899  in  New  Jersey.     Journ.  Myc.  5 :  201-2.     1889. 

Reports  this  later  very  abundant  and  injurious  outdoors  upon 
squash,  pumpkin  and  cucumbers. 

15.  Halsted,    B.    D.      Notes    upon    Peronosporae    for    1890.      Bot.    Gaz. 

15 :  322.     1890. 
Notes  the  absence  of  cucumber  mildew  this  year  in  N.  J. 

16.  Halsted,   B.   D.      Notes   upon   Peronosporeae   for   1891.      Bot.   Gaz. 

16:339.     1891. 

Notes  prevalence  of  Peronospora  Cubensis  B.  &  C.  in  1891 ; 
lists  from  N.  J.,  Dist.  Col.,  and  Conn,  (on  watermelon). 

17.  Halsted,   B.    D.     Peronospora   Cubensis   B.    &   C.    (Cucumber   Mil- 

dew).    N.  J.  Agr.  Exp.  Stat.  Rept.  12:248.     1892. 

Notes  prevalence  of  this  fungus  in  1891  in  N.  J.  and  elsewhere ; 
states  Sturgis  found  it  in  Conn,  on  watermelon. 

18.  Halsted,  B.  D.     Fungous  Diseases  of  the  Muskmelon.     N.  J.  Agr. 

Exp.  Stat.  Rept.  14:352-3.     1894.     [Illustr.] 

Briefly  describes  damage  done  by  downy  mildew. 

19.  Halsted,   B.   D.     The  Downy  Mildew    (Plastnopara  Cubensis  B.  & 

C).     N.  J.  Agr.  Exp.  Stat.  Rept.  15:348,  350,  359-     i895- 
Lists  on  cucumbers,  musk  melons  and  squash  from  N.  J. 

20.  Halsted,  B.  D.     Bordeaux  with  Cucumbers.     N.  J.  Agr.  Exp.  Stat. 

Rept.  16: 327.     1896. 


LITERATURE    ON    MELON    BLIGHT.  357 

Notes  favorable  results  from  spraying  against  downy  mildew, 
etc.,  since  the  sprayed  plants  lived  one  month  longer  than  those 
not  sprayed. 

21.  Halsted,   B.   D.      Experiments  with   Cucumbers.      N.  J.   Agr.   Exp. 

Stat.  Rept.  17  :  340-44.     1897. 

Sprayed  plants  with  Bordeaux,  soda  Bordeaux,  potash  Bordeaux, 
but  results  of  little  importance  in  determining  value  in  preventing 
downy  mildew,  as  this  was  not  present. 

22.  Halsted,   B.   D.      Experiments  with  Cucumbers.      N.  J.   Agr.   Exp. 

Stat.  Rept.  18:  319-22.     1898. 

Reports  Bordeaux  and  potash  Bordeaux  as  useful  in  preventing 
the  downy  mildew. 

23.  Halsted,  B.  D.     The  Blight  of  Cucumbers.     N.  J.  Agr.  Exp.  Stat. 

Rept.  22  :  437,  440.     1902. 

Notes  that  this  was  common  in  N.  J.  in  1901,  and  destroyed  most 
of  the  musk  melons ;  a  plot  of  cucumbers  was  kept  in  full  leaf 
and  vigor  by  spraying  with  soda  Bordeaux. 

24.  Hecke,  L.     Ueber  das  Auftreten  von  Plasmopara  cubensis  in  Oster- 

reich.     Ann.  Myc.  2  :  355-8.     1904. 

Reports  the  mildew  from  Vienna,  Austria,  on  cucumbers ;  gives 
historical  and  botanical  account  of  fungus. 

25.  Hecke,  L.     Ueber  das  Auftreten  von  Plasmopara  cubensis  in  Oster- 

reich.      Zeit.    Landw.    Ver.    Oester.    1904.      [Review,    Bot.    Centr. 
95 :  640-41.     1904-] 

Notes  presence  in  Austria  on  cucumbers ;  gives  distribution, 
history,  etc. 

26.  Hennings,  P.     Fungi  S.  Paulenses  I.     Hedw.  41 :  104.     1902. 

Lists  Peronospora  cubensis  B.  et  C.  on  Cucumis  sativus  from 
Sao  Paulo,  S.  Amer.,  collected  in  1900. 

27.  Hume,  H.  H.     Downy  Mildew  of  the  Cucumber.     Ann.  Rept.  Fla. 

Agr.  Exp.  Stat.  12-13  '■  3°-     IQOO- 

Reports  this  serious  in  Fla.  on  cucumber;  states  that  it  lives 
there  throughout  the  year ;  gives  short  botanical  and  historical 
account  of  fungus,  and  reports  successful  spraying  experiments  by 
a  grower. 

28.  Humphrey,  J.   E.      The .  Cucumber   Mildew. — Plasmopara   Cubensis 

(B.  &  C.)  Humph.     Ann.  Rept.  Mass.  Agr.  Exp.  Stat.  1890:210-2. 
1891.     [Illustr.] 

Notes  injury  in  Mass.  to  cucumbers  and  squash  by  Peronospora 
Cubensis  B.  &  C,  which  he  here  places  under  the  genus  Plas- 
mopara;  notes  structure  and  germination  of  fungus. 

29.  Humphrey,  J.  E.     The  Downy  Mildew. — Plasmopara  Cubensis   (B. 

&    C.)    Humph.     Dept.    Veg.    Path.    Mass.    St.    Exp.    Stat.    1902: 
1S-19. 

Notes  its  injury  to  cucumbers  grown  in  greenhouse. 

30.  Jaczewski,  A.  de.     Note  sur  le  Peronospora  cubensis  B.  et  C.     Rev. 

Myc.  22  :  45-7.     1900.     [Illustr.] 
28 


358         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

Reports  Plasinopara  australis  on  Scliizopepo  hryoniacfolius  col- 
lected in  Manchuria  in  1876  [not  P.  Cubcnsis  as  reported  by 
Hecke]  ;  calls  attention  to  differences  between  these  two  mildews, 
and  gives  scientific  description  of  P.  Cubensis,  but  makes  mistake 
in  calling  conidia  hyaline. 

31.  Jaczewski,   A.   de.      Plasinopara   Cubensis.      Bull.   Torr.    Bot.    Club 

29  :  649.     1902. 

Notes  presence  of  this  fungus  in  Russia. 

32.  Kornauth,  K.     Ueber  in  Jahre  1903  beobachtete  Pflanzenkrankheiten. 

Zeitschr  Landw.  Vers.  Oester.   1904:159.     [Review,   Centr.   Bakt. 
Par.  Infek.  13  :  461.] 

Notes  presence  of  Peronospora  Cubensis  on  cucurbitaceous  plant 
in  Vienna  greenhouse. 

33.  Lamson,  H.  H.     Downy  Mildew  of  the  Cucuinber  and  Musk  Melon. 

N.  Hamp.  Agr.  Exp.  Stat.  Bull.  87:  129.     1901. 

Notes  this  fungus  injurious  to  cucumbers  and  musk  melons  in 
N.  Hamp. ;  spraying  experiments,  begun  after  appearance  of  the 
disease,  did  no  good. 

34.  Lamson,  H.  H.     Fungous  Diseases  and  Spraying.     N.  Hamp.  Agr. 

Exp.  Stat.  Bull.  loi :  63,  64.     1903. 

Reports  favorable  results  from  spraying  cucumbers  and  musk 
melons  with  Bordeaux  beginning  about  the  middle  of  July;  applied 
five  times  at  intervals  of  about  10  days. 

35.  Linhart.     Die  Peronospora-recte  Pseudoperonospora  Krankheit  der 

Melon  und  Gurken  in  Ungarn.     Zeits.  Pflanzenk.  14:  143-45.     I904- 
Reports  severe  outbreak  of  downy  mildew  on  cucumbers,  musk 
and  watermelons  in  Hungary  in  1903. 

36.  Massee,  G.     Cucumber  and  Melon  Mildew.     A  Text  Book  of  Plant 

Diseases :  80.     1899. 

Notes  its  recent   introduction  into   England,  on  Cucurbita  pepo 
and  Cticuniis  saliva,  from  Japan. 
27.  Orton,  W.  A.     Plant  Diseases  in  the  United  States  in  1901.     Year- 
book U.  S.  Dept.  Agr.  1901 :  670.     1902. 

Notes  downy  mildew  did  damage  to  musk  melons  in  Long  Island, 
N.  Y.,  Mass.,  Conn.,  N.  J. 

38.  Orton,  W.  A.     Plant  Diseases  in  the  United  States  in  1902.     Year- 

book U.  S.  Dept.  Agr.  1902 :  717.     1903. 

Reports  downy  mildew  injurious  to  cucumbers  and  musk  melons 
in  southern  New  England. 

39.  Orton,  W.  A.     Plant  Diseases  in  1903.     Year  Book  U.  S.  Dept.  Agr. 

1903 :  553-     1904- 

Reports  downy  mildew  causing  large  loss  of  cucumbers  in 
Florida  and  S.  Car. ;  also  destructive  in  West  Virg.,  Penn.,  N.  Y. 
and  Mich. ;    occurred  in  Ohio,  Mass.,  Conn.,  R.  I. 

40.  Rostowzew,  S.  J.     Beitrage  zur  Kenntnis  der  Peronosporeen.     Flora 

92:405-30.     1903.     [Illustr.] 

Describes  a  new  var.,  Tweriensis,  of  the  downy  mildew,  from 
the  province  Twer,  Russia;  places  this  and  the  species  under  a 
new  genus,   Pseudoperonospora;    gives   detailed  botanical  account 


LITERATURE   ON    MELON    BLIGHT.  359 

of  the  mildew;    describes  immature  oospores;    gives  experiments 
with  infected  soil,  etc. 

41.  Saccardo,   D.     Plaswopara   Cubensis    (B.   &   C.)    Humphrey.     Myc. 

Ital.     1276. 

Issues  specimens  from  Italy  and  states  conidia  are  22-25  by 
15-17M  hyaline,  finally  olive  brown,  and  not  violet,  as  reported  by 
Humphrey. 

42.  Saccardo,  P.  A.     Notae  mycologicae.     Ann.  Myc.  2 :  14.     1904. 

Notes  mildew  was  found  on  Cucuinis  Melo  at  Selva  (Treviso), 
Italy,  in  1903. 

43.  Selby,  A.  D.     Downy  Mildew  of  Cucumbers.     Ohio  Agr.  Exp.  Stat. 

Bull.  72, :  234.     1897. 

Notes  prevalence  in  Ohio  on  cucumbers  in  greenhouses  and  also 
outdoors. 

44.  Selby,    A.    D.      Cucumber    Diseases.      Ohio    Agr.    Exp.    Stat.    Bull. 

89:99-116.     1897. 

Notes  very  injurious  effect  of  downy  mildew  on  late  or  pickling 
cucumbers  in  Ohio,  especially  in  1897;  gives  botanical  account  of 
fungus ;    records  successful  spraying  experiments  with  Bordeaux. 

45.  Selby,  A.  D.     Studies  of  the  Diseases  of  Cucurbits  and  Tomatoes. 

Ohio  Agr.  Exp.  Stat.  Bull,  in:  140-41.     1899. 

Refers  to  work  done  by  Ohio  Station  in  study  and  prevention  of 
downy  mildew  of  cucumbers,  etc. 

46.  Selby,   A,    D.     Further   Studies   of   Cucumber,   Melon   and   Tomato 

Diseases,  with  Experiments.     Ohio  Agr.  Exp.  Stat.  Bull.  105 :  219- 
21,  223-29,  230-1.     1899. 

Gives  notes  on  downy  mildew ;  also  list  of  hosts  upon  which  it 
spread  in  the  disease  garden ;  gives  successful  spraying  experi- 
ments with  Bordeaux  on  cucumbers,  and  chiefly  unsuccessful  ones 
on  musk  melon. 

47.  Selby,  A.  D.     Additional  Host  Plants  of  Plasniopara  cubensis.     Bot. 

Gaz.  27  :  67-8.     1899. 

Grew  a  large  number  of  cucurbits  in  a  disease  garden  on  most 
of  which  the  mildew  spread  from  the  ordinary  hosts.  (See  hosts 
elsewhere  in  this  article.) 

48.  Selby,  A.   D.     Certain  troublesome  Diseases  of  Tomatoes  and  Cu- 

curbits.    Reprint  Journ.  Columbus  Hort.  Soc.  11:    i. 

Notes  downy  mildew  becoming  common  in  Ohio,  especially  in 
greenhouses. 

49.  Selby,  A.  D.     A  Condensed  Handbook  of  the  Diseases  of  the  Culti- 

vated Plants  in  Ohio.     Ohio  Agr.  Exp.  Stat.  Bull.  121  :  29,  33,  38, 
SI,  54,  58.     1900. 

Gives  short  notes  on  downy  mildew  under  the  following  hosts : 
cucumber,  gourd,  musk  melon,  pumpkin,  squash  and  watermelon. 
so.  Selby,  A.  D.     Calendar  for  Treatment  of  Plant  Diseases  and  Insect 
Pests.     Ohio  Agr.  Exp.  Stat.  Bull.  147:  50,  SI.     1904. 

Recommends  for  downy  mildew  of  cucumber  and  musk  melon 
at  least  four  sprayings  with  Bordeaux,  at  intervals  of  eight  to  ten 
days,  beginning  about  the  time  the  vines  start  to  run. 


360         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

51.  Sirrine,    F.    A.   and    Stewart,    F.   C.     Spraying   Cucumbers    in   the 

Season  of  1898.     N.  Y.  Agr.  Exp.  Stat.  Bull.  156:376-96.     1898. 

Give  very  favorable  results  of  several  spraying  experiments  with 
Bordeaux  made  on  a  large  scale  with  pickling  cucumbers ;  recom- 
mend first  treatment  July  15  to  August  i,  repeating  every  eight  to 
ten  days  until  frost;  give  cost  of  spraying,  yields  and  profits  in 
their  experiments. 

52.  Stene,  A.  E.     When  to  Spray.     R.  I.  Agr.  Exp.  Stat.  Bull.  100:  127. 

1904. 

Notes  downy  mildew  difficult  to  control,  recommends  Bordeaux 
beginning  middle  of  July  and  repeating  every  ten  to  twelve  days 
during  season  of  vines. 

53.  Stewart,  F.  C.     The  Downy  Mildew  of  the  Cucumber;    what  it  is 

and  how  to  prevent  it.     N.  Y.  Agr.  Exp.  Stat.  Bull.  119:  155-82. 
J897.     [Illustr.] 

Gives  general  and  botanical  account  of  this  fungus,  which  was 
serious  in  New  York  in  1896;  reports  very  successful  spraying 
experiments  with  Bordeaux  on  late  cucumbers ;  recommends 
spraying  the  young  plants  and  repeating  every  eight  to  ten  days 
till  frost. 

54.  Stewart,    F.    C.      Further    Experiments    on    Spraying    Cucumbers. 

N.  Y.  Agr.  Exp.  Stat.  Bull.  138 :  636-44.     1897. 

Gives  favorable  results  from  spraying  early  cucumbers  with 
Bordeaux  (i  to  8  formula)  to  prevent  downy  mildew  in  1897; 
notes  impractical  results  of  trying  to  prevent  mildew  by  shad- 
ing with  corn ;   reports  new  host,  Cucumis  moschata. 

55.  Stone,  G.   E.   and   Smith,   R.   E.     Cucumber  Mildew    (Plasmopara 

Cubensis  B.  &  C).     Mass.  Agr.  Exp.  Stat.  Rept.  13:72-3.     1901. 
Note  appearance  on  greenhouse  cucumbers  in  Mass. 

56.  Stone,  G.  E.  and  Smith,  R.  E.     Melon  Failures.     Mass.  Agr.  Exp. 

Stat.  Rept.  14 :  62-6.     1902. 

Report  downy  mildew  with  Alternaria  and  CoUetotrichum,  the 
cause  of  unusual  failure  of  musk  melons ;  also  bad  on  cucumbers ; 
spraying  not  entirely  effective  with  musk  melon,  but  advocated. 

57.  Stone,  G.  E.  and   Smith,   R.   E.     Report  of  the  Botanists.     Mass. 

Agr.  Exp.  Stat.  Rept.  15 :  28,  29-32,  37-8.     1903. 

Give  general  notes  on  prevalence  of  downy  mildew  on  cucumber 
and  musk  melon  in  Mass. ;  note  growth  of  plants  under  tents ; 
think  mildew  can  be  kept  off  from  plants  grown  in  greenhouse 
by  proper  watering ;    report  little  gain  from  spraying  musk  melons. 

58.  Stone,  G.  E.     Cucumbers  under  Glass.     Mass.  Agr.  Exp.  Stat.  Bull. 

87 :  36-7.     1903.     [Illustr.] 

Gives  general  account  of  the  downy  mildew  and  preventive 
measures. 

59.  Sturgis.  W.  C.     Downy  Mildew  on  Melons.     Conn.  Agr.  Exp.  Stat. 

Rept.  1899 :  277-78.     1900. 

Gives  account  of  damage  done  at  Meriden,  Conn.,  on  musk 
melons  and  advocates  starting  plants  under  glass  to  get  an  earlier 
start  and  escape  in  part  this  trouble. 


LITERATURE   ON    MELON    BLIGHT.  36 1 

60.  Swingle,  W.  T.     Some  Peronosporaceae  in  the  Herbarium  of  the 

Division  of  Vegetable  Pathology.     Journ.  Myc.  7 :  125.     1892. 

Lists  Peronospora  cubensis  B.  &  C,  under  doubtful  section  of 
this  genus,  on  Cucumis  anguria  from  Texas  and  Florida,  and  on 
Cucumis  sativus  from  Texas  and  Maryland. 

61.  Thaxter,   R.     Peronospora   on   Cucumbers.     Conn.   Agr.   Exp.    Stat. 

Rept.  1890: 97.     1891. 

Notes  appearance  of  this  fungus,  for  first  time  in  Connecticut, 
at   South   Manchester. 

62.  Tubeuf  and  Smith.     Peronospora  (Plasmopara)  cubensis.     Diseases 

of  Plants:    134.     1897. 

Merely  list  as  an  injurious  species. 

63.  Waite,   M.   B.      Description   of  two   New   Species   of    Peronospora. 

Journ.  Myc.  7  :  106.     1892. 

Notes  the  resemblance  of  his  Peronospora  Celtidis,  n.  sp.,  on 
Celtis  occidentalis  to  Peronospora  Cubensis  B.  &  C. 

64.  Weed,    C.     The    Cucumber   Mildew.     Fungi    and    Fungicides :     160. 

1894- 
Gives  short  account  of  the  fungus. 

65.  Zimmermann,  A.    Ueber  einige  an  tropischen  Kulturpflanzen  beo- 

bachtete  Pilze  II.     Centr.  Bakt.  P^r.  Infek.  8:  148.    1902.    [Illustr.] 
Describes  Peronospora  cubensis  var.  atra,  n.  var.,  from  Buiten- 
zorg,  Java,  or  Cuciirbita  pepo. 

66.  Zimmermann,   A.      Untersuchungen  iiber   tropische   Pflanzenkrank- 

heiten.     Ber.  iiber  Land-  und  Forstwirtschaft  in  Deutsch-  Ostafrika 
2:11-36.     [Review,  Centr.  Bak.  Par.  Infekt.  12:316.     1904-] 

Lists  Peronospora  cubensis  var.  atra  on  cucumber  leaves  from 
Dutch  East  Afrika. 

Explanation  of  Plate  XXXI. 

Detailed  drawings  of  P eronoplasmo para  Cubensis.  Magni- 
fied about  600  diameters,  except  i,  which  is  only  magnified 
about  350  diameters. 

1.  A  single  conidiophore  emerging  from  a  stomate  of  a  leaf. 

2.  Base  of  a  conidiophore  and  lobes  of  the  mycelium  from 
which  other  conidiophores  develop  in  favorable  weather. 

3.  Top  of  a  conidiophore,  showing  an  immature  (a)  and  a 
mature  (b)  spore  still  attached. 

4-9.  Spores  (temporary)  that  were  produced  on  the  conidio- 
phores.    4.  Contents  emptied  out  through  pore  of  dehiscence. 

5.  Spore  about  to  germinate,  showing  areas  in  the  protoplasm. 

6.  Showing  last  of  about  a  dozen  zoospores  escaping  from  the 
spore.     7.  A  zoospore  that   failed  to  escape   from  the:   spore. 


362         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

8.  Cross  section  of  an  empty  spore.     9.  Empty  spore,  showing 
the  pore  through  which  the  zoospores  escaped. 

10-12.  Motile  stage  of  the  zoospores ;  10,  showing  the  sepa- 
ration of  zoospores  into  individuals. 

13.  An  unusually  large  zoospore  making  an  unsuccessful 
attempt  to  divide. 

14.  Zoospores  after  coming  to  rest  and  before  their  ger- 
mination. 

15.  Zoospores  (in  an  amoeboid  condition)  that  never  germi- 
nated and  finally  died. 

16.  Different  stages  of  the  germination,  in  water,  of  the 
resting  zoospores. 

17-20.  Infection  of  the  host  through  germinating  zoospores 
resting  on  the  epidermis.  17.  A  zoospore  settled  down  over  a 
stomate.  18.  The  same  zoospore  two  hours  later,  with  its  germ 
tube  apparently  entering  the  leaf  between  the  guard  cells  of  the 
stomate.  19-20.  A  resting  zoospore  (a)  on  leaf  near  a  stomate  ; 
(b)  its  final  position  after  starting  to  germinate  two  hours  later ; 
20,  its  condition  twenty-four  hours  later,  apparently  trying  to 
bore  into  leaf  through  the  epidermis. 


PLATE  XXIX. 


a.   Under  surface  of  leaf  showing  early  stage  of  blight. 


b.    Under  surface  of  leaf  showing  later  stage  of  blight. 


BLIGHT,  OR   DOWNY   MILDEW,  OF    MUSK    MELON,   Pcronoplasinopara   Ctihmsis,   p.   344. 


^:^- 


1^^^ 


:-.*:^^- 


a.   Blighted  vine  in  the  field,  p.  344. 


b.   Vines  in  foreground  sprayed  ;  those  in  rear  not  sprayed,  p.  351. 
BLIGHT  OR   DOWNY   MILDEW  OF   MUSK   MELON. 


PLATE  XXXI. 


DETAILED   DRAWINGS  OF  Peronoplasmopaya   Ciihcns 


BLIGHT    OF    POTATOES.  365 

DOWNY  MILDEW,  OR  BLIGHT,  Phyfophthora  infestans 
(Mont.)   DeBy.,  OF  POTATOES. 

Aim  of  Investigations.  In  1902  the  writer  began  a  series  of 
spraying  experiments  with  potatoes  having  two  objects  in  view, 
namely,  first,  to  determine  just  how  injurious  the  bhght  fungus, 
Phytophthora  infestans,  is  in  this  state  year  after  year,  and 
second,  to  determine  the  most  effective  and  practical  method  of 
spraying  to  prevent  it.  No  especial  originality  is  claimed  for 
these  experiments,  since  the  object  was  to  apply  chiefly  what 
the  general  results  of  others  had  determined  and  see  how  these 
were  adapted  to  the  conditions  that  exist  here.  -We  report  in 
this  paper  the  results  and  suggestions  that  have  been  gained 
so  far. 

No  idea  was  had  at  the  start  of  a  special  study  of  the  fungus 
that  is  responsible  for  blight,  as  it  has  had  the  attention  of  many 
European  botanists.  There  are  a  number  of  points  in  its  life 
history,  however,  that  the  writer  has  been  forced  to  believe  are 
not  known,  or  at  least  have  not  been  positively  settled.  A  com- 
plete knowledge  of  the  fungus  must  have  considerable  bearing 
in  determining  the  very  best  ways  for  controlling  the  disease. 
Consequently,  during  the  past  year,  efforts  have  been  made  to 
gain  all  possible  information  concerning  the  fungus  itself. 
This  second  phase  of  the  subject  is  not  dealt  with  especially  in 
this  paper,  as  it  is  still  under  consideration,  but  as  a  general 
knowledge  of  the  blight  fungus  is  necessary  to  an  intelligent 
understanding  of  the  methods  employed  in  combating  it,  we  give 
briefly  what  we  understand  from  our  own  observations  and 
those  of  others  to  be  the  main  facts  in  its  life  history. 

Life  History  of  Fungus. 

Infected  Tubers.  To  the  ordinary  observer  blight  begins  in 
his  field  when  it  shows  with  the  sudden  or  gradual  death  of  the 
vines  in  the  middle  of  July  or  later.  Its  first  development, 
though  hidden,  really  began  when  infected  tubers  in  that  or 
some  other  field  were  planted  in  the  spring.  In  other  words, 
the  blight  fungus  is  carried  over  the.  winter  in  the  tubers  from 
a  previous  diseased  crop.  Furthermore,  so  far  as  we  nozv 
knozv,  the  fungus  is  perpetuated  only  by  tlie  infected  tubers, 


364         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

and  not  through  diseased  tubers  that  have  rotted  outdoors,  or 
by  the  old  rotted  vines,  or  through  infection  of  the  land,  or  on 
some  other  host  of  the  fungus.  However,  there  is  a  possibility 
that  one  or  more  of  these  other  means  may  also  serve  to  per- 
petuate the  fttngus,  but  as  yet  proof  is  lacking.  A  good  deal 
of  study  has  been  made  on  this  phase  of  the  subject,  but  it  needs 
still  more. 

The  appearance  of  the  disease  as  ordinarily  shown  at  time 
of  storage  on  potatoes  is  a  reddish  brown  rot  that  develops  only 
slowly,  if  at  all,  when  the  tubers  become  dried  out  and  are  kept 
in  a  cool,  dry  place.  This  discoloration  shows  at  the  surface, 
often  extending  inward  from  the  skin  to  the  bundles  or  further, 
and  the  surface  may  also  become  slightly  sunken  or  pitted. 
(See  Plate  XXXIII,  b.-c.)  In  the  fields,  and  while  still 
damp  in  storage,  the  rotting  is  often  very  rapid.  This  is  largely 
due  to  the  presence  of  bacteria  or  the  Fusarium  fungus  that 
develop  independently  or  as  a  consequence  of  the  blight  and  are 
apparently  more  active  agents  of  decay.  Very  often  tubers  are 
found  having  an  end  rot,  usually  the  stem  end,  that  affects  the 
whole  tuber  as  it  progresses  forward.  Not  infrequently  the 
freshly  diseased,  or  innermost,  tissues  have  the  same  reddish 
brown  color  found  in  blighted  tubers,  and  probably  the  fungus 
is  sometimes  present,  but  usually  this  end  rot  seems  to  be  caused 
by  the  Fusarium  fungus  which  breaks  out  in  white  fruiting 
pustules  on  the  surface.  This  also  becomes  a  slow  dry  rot  in 
storage  after  the  tubers  have  dried  out.  The  bacterial  trouble 
is  usually  shown  in  the  field  by  a  slimy,  sticky,  ill-smelling  rot 
that,  if  first  started  by  the  blight  fungus,  soon  outstrips  it  as 
the  agent  of  decay  and  no  doubt  often  starts  independently  of 
this  fungus.  In  storage  it  gradually  dries  out  and  works  slower 
and  is  often  found  in  connection  with  the  Fusarium  or  other 
fungi. 

The  blight  fungus  persists  in  the  infected  tubers  by  means  of 
its  mycelium,  or  its  vegetative  stage.  This  consists  of  micro- 
scopic threads  that  have  pushed  their  way  slowly  between  the 
cells  of  the  tuber,  occasionally  sending  short,  thick-walled 
branches  inside  the  cells  to  obtain  nourishment  for  growth. 
This  stage  has  directly  to  do  with  rotting  the  tubers  and  blight- 
ing the  vines,  but  not  with  spreading  the  disease.  During  the 
storage  of  the  tubers  it  apparently  exists  in  a  dormant,  or  at 
least  not  very  active,  condition. 


BLIGHT    OF    POTATOES.  365 

When  infected  tubers  are  planted  in  the  spring  the  myceHum 
may  push  out  on  the  undiseased  cut  surface  of  the  tuber  from 
the  diseased  tissue  and  there  form  the  temporary  spore,  or 
reproductive  stage,  the  same  that  it  develops  in  July  or  August 
on  the  leaves.  This  spore  development  is  likely  to  continue  only 
for  a  short  time,  as  the  blight  fungus  is  easily  crowded  out  by 
other  fungi  and  it  does  not  form  this  stage  at  all  on  rotten 
tissues.  Some  of  the  spores  produced  here  may  be  carried  acci- 
dentally by  insects  or  washed  by  the  rains  to  the  young  buds  of 
the  sprouting  tuber  and  on  germination  infect  these  with  the 
disease.  Or  probably  the  mycelium  as  often  grows  directly 
from  the  diseased  tissue  into  the  healthy  tissue  of  the  develop- 
ing buds  and  secures  infection  in  this  way.  It  is  quite  probable 
that  comparatively  few  plants  in  the  field  become  infected 
through  the  diseased  tubers  ;  at  least  we  can  say  positively  from 
experiments  that  diseased  tubers  do  not  necessarily  produce 
infected  plants.  In  an  experiment  by  the  writer  where  badly 
rotted  blight  tubers  were  planted  in  a  greenhouse,  the  tubers 
either  failed  entirely  to  produce  plants  or  else  developed  plants 
in  which  the  disease  never  appeared,  though  the  fungus  grew 
out  on  the  cut  surface  in  its  spore  stage.  So  far  the  writer  has 
not  observed  in  the  fields  stems  developed  from  infected  buds, 
but  the  few  seen  in  the  greenhouse  remained  dwarfed  and  of  a 
reddish  brown  color  at  the  surface,  as  if  the  fungus  was  super- 
ficial in  the  tissues.  These  infected  stems  do  not  produce  spores 
except  under  proper  conditions  of  moisture.  This  fact,  together 
with  their  scarcity,  possibly  explains  why  the  disease  is  so  slow 
in  getting  started  in  a  field,  rarely  ever  appearing  before  the 
middle  of  July,  and  often  much  later.  Once  the  spores  begin 
to  be  produced  above  ground,  however,  with  proper  weather 
conditions  they  spread  the  disease  through  the  field  and,  no 
doubt,  to  other  fields.  Just  how  far  and  how  often  the 
fungus  is  carried  by  these  spores  from  one  field  to  another  are 
points  that  need  further  investigation.  Also  the  whole  subject 
of  the  very  early  development  of  the  disease  requires  more 
observations  and  experiments. 

Blighted  Vines.  This  temporary  spore  stage  may  be 
described  very  briefly  as  follows :  The  fungus  once  started  in 
a  leaf,  through  infection  from  a  germinating  spore,  develops 
its  mycelium  between  leaf  cells,  killing  the  tissues  as  it  goes, 


366         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

and  also  sends  out  to  the  exterior  through  the  stomates,  or  open- 
ings in  the  epidermis,  erect  branched  fertile  threads  that  form 
the  temporary  spores.  The  spores  mature  very  quickly  and 
can  germinate  immediately  if  they  fall  in  a  drop  of  water. 
Many  of  the  spores  perish,  however,  as  they  cannot  live  long 
in  dry  air.  The  germination  usually  consists  in  the  formation 
and  liberation  of  several  motile  animal-like  bodies  called 
zoospores  that  swim  around  in  the  water  for  a  short  time  and 
then  come  to  rest.  They  then  send  out  a  germ  thread  that 
grows  into  the  leaf  tissues  and  develops  the  mycelium  from 
which  arise  the  spore-bearing  threads  as  before.  This  process 
of  spore  formation,  germination,  infection  and  development  of 
mycelium  can  be  kept  up  indefinitely,  or  at  least  as  long  as 
weather  conditions  are  favorable  and  there  are  green  potato 
leaves  left.  The  wind,  rain  and  insects  serve  in  spreading  the 
spores.  Moist,  cloudy  weather  of  several  days'  duration  is 
best  adapted  for  the  growth  and  spread  of  the  fungus,  since  the 
fruiting  threads  are  then  formed  most  abundantly ;  then  con- 
ditions are  also  favorable  for  the  germination  of  the  spores  and 
infection  of  the  leaves  and  the  diseased  area  in  the  leaf  develops 
rapidly.  In  dry  weather  the  blackened,  diseased  tissues  of  the 
leaf  dry  up,  but  the  fungus  makes  very  little  further  advance, 
while  very  few  new  fertile  threads  are  developed  on  the  exterior. 
The  blackened,  diseased  spots  usually  start  at  the  margin  of  the 
leaves  and  develop  inward,  and  on  the  under  side  the  spore 
threads,  especially  in  moist  weather,  can  be  seen  as  a  faint 
whitish  growth  just  in  advance  of  the  discoloration.  (See  Plate 
XXXII,  a.)  The  character  of  the  weather  during  July  and 
August  determines  largely  how  much  injury  the  fungus  will  do 
to  the  vines.  If  after  the  disease  has  spread  somewhat  through 
the  fields  there  comes  a  period  of  blight  weather,  the  vines  may 
all  be  gone  in  a  week ;  or  if  the  weather  is  less  favorable  for 
its  development  the  disease  may  lag  along  slowly.  Some 
seasons  it  does  not  appear  until  the  very  end. 

Rotten  Tubers.  It  has  been  stated  by  some  writers  that  the 
blight  fungus,  through  its  mycelium,  passed  down  the  stems 
into  the  tubers.  We  have  seen  no  evidence  that  this  is  so,  and 
doubt  if  it  ever  (perhaps  rarely)  occurs.  With  the  Fusarium 
and  the  bacterial  rots  of  the  tubers  this  may  be  true,  since  the 
disease  in  these  cases  often  starts  in  the  stem  end  of  the  tubers. 


BLIGHT    OF    POTATOES.  367 

Infection  of  the  blighted  tubers  takes  place  through  the  spores 
that  fall  on  the  ground  from  the  infected  leaves  above.  If 
these  are  washed  down  to  the  tubers,  infection  takes  place  on 
their  germination  by  the  germ  threads  boring  directly  into  the 
tissues  and  there  developing  the  mycelium.  So  far  as  observed 
by  the  writer,  the  fungus  is  not  apt  to  send  out  fruiting  threads 
on  the  surface  of  these  tubers  while  in  the  ground  and  spread 
the  disease  this  way.  Such  fruiting  threads,  however,  have 
been  seen  in  potatoes  freshly  dug  and  kept  in  a  moist  atmos- 
phere, and  probably  are  formed  somewhat  in  the  ground.  The 
amount  of  moisture  in  the  soil  while  these  spores  fall  on  the 
ground  and  the  nearness  of  the  tubers  to  the  surface  are  two 
factors  in  determining  the  extent  of  the  infection.  Severity  of 
blight  in  the  foliage  does  not  necessarily  mean  a  corresponding 
severity  of  rot  in  the  tubers.  At  least  in  July,  1902,  there  was 
a  sudden  and  severe  blighting  of  the  vines,  many  fields  being 
entirely  dead  a  week  after  the  appearance  of  the  trouble,  and 
yet  there  was  comparatively  little  complaint  of  rot  that  year. 
On  the  other  hand,  in  1904  the  blight  made  its  appearance  very 
late  in  the  fields,  doing  comparatively  little  injury  to  the  foliage  ; 
but  this  year  the  tubers  rotted  badly  from  the  blight.  The  rot 
in  the  tubers  does  not  usually  start  until  the  vines  are  dead. 
As  mentioned  before,  all  the  rots  of  the  tubers  are  not  due  to 
the  blight  fungus.  In  1903,  for  instance,  the  tubers  rotted 
rather  badly,  but  this  was  caused  chiefly  by  the  bacterial  rot 
and  the  Fusarium  fungus. 

Winter  Spores.  The  spores  of  the  blight  fungus  are  tem- 
porary and  cannot  carry  the  fungus  over  the  winter,  but,  as 
previously  stated,  this  is  accomplished  by  the  mycelium  in  the 
infected  tubers.  Many  of  the  fungi  in  the  group  to  which  the 
blight  fungus  belongs,  however,  develop  thick-walled  oospores 
(winter  or  resting  spores),  and  these  serve  as  a  means  of  per- 
petuating such  fungi.  These  spores  have  been  looked  for  in 
connection  with  the  potato  fungus,  but  their  existence  has  never 
positively  been  proven,  though  some  investigators  have  thought 
that  they  found  them.  The  writer  has  made  a  special  search 
for  them,  and  while  some  suspicious  things  have  been  seen, 
no  positive  evidence  of  their  existence  has  been  gained,  though 
artificial  cultures  of  the  fungus  have  been  grown  on  various 
media  in  test  tubes  and  search  has  been  made  in  the  potato 


368         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

leaves  and  tubers  in  all  stages  of  infection  and  decay.  From 
these  investigations  we  are  inclined  to  the  belief  that  if  such 
spores  are  formed  in  this  locality  they  develop  only  in  the  rotted 
tissues,  tubers  most  likely  in  the  very  last  stages  of  their  complete 
decay ;  that  is,  in  the  late  spring  in  the  tubers  left  in  the  fields, 
and  later  in  the  summer,  after  rotting  to  pieces,  in  the  infected 
seed  tubers.  Blighted  tubers  in  this  condition  not  infrequently 
contain  spores  of  this  nature  that  look  suspicious,  but  as  yet  no 
positive  proof  of  their  connection  has  been  obtained,  and  as  a 
number  of  unrelated  saprophytic  fungi  develop  in  the  rotted 
tubers  they  could  easily  belong  to  some  of  these.  It  has 
occurred  to  the  writer,  also,  that  possibly  these  oospores  are 
formed  only  on  the  union  of  two  strains  of  mycelia  (which  may 
rarely  occur  together),  as  has  recently  been  shown  for  a  some- 
what related  group  of  fungi.  In  any  case,  whether  this  fungus 
possesses  such  spores  or  not,  further  study  along  this  phase  of 
the  subject  is  needed. 

Spraying  Experiments. 

Previous  Experiments.  Both  the  former  botanists  of  this 
Station  made  a  few  spraying  experiments  that  may  be  briefly 
mentioned  here.  Professor  Thaxter,  in  1889,  when  blight  was 
unusually  severe,  made  one  of  the  very  first  spraying  experi- 
ments against  this  trouble  that  has  been  reported.  He  sprayed 
three  times  with  Bordeaux  mixture,  on  July  18,  July  25  and 
August  3,  and  got  a  decided  difiference  in  the  foliage  between 
those  sprayed  and  those  unsprayed.  On  August  3  the  sprayed 
vines  retained  50  to  60  per  cent,  of  their  foliage,  while  the 
unsprayed  were  entirely  dead,  arid  on  August  10  the  sprayed 
vines  still  retained  25  per  cent,  of  their  foliage.  Unfortunately 
(Thaxter  thought  possibly  due  to  error  in  harvesting)  the 
treatment  gave  no  increase  in  yield.  In  1890  Thaxter  reported 
a  successful  treatment  by  Mr.  N.  S.  Piatt,  made  after  the  blight 
appeared  in  the  field ;  in  this  case  the  yield  was  reported  con- 
siderably increased.  Dr.  Sturgis  also  conducted  spraying 
experiments  in  1892  and  in  1893,  but  both  these  years  there  was 
little,  if  any,  blight  in  the  sprayed  fields,  so  that  his  experiments 
were  chiefly  of  value  in  showing  what  effect  spraying  has  in 
vears  when  blight  is  not  troublesome.     He  reported  consider- 


SPRAYING    FOR    POTATO    BLIGHT.  369 

able  benefit  resulting  from  the  treatment  the  first  year,  but  not 
the  second,  which  was  a  very  dry  year. 

Recent  Experiments.  The  following  experiments  have  been 
made  personally  by  the  writer  in  order  that  he  might  learn  of 
the  disadvantages  as  well  as  the  advantages  of  spraying.  They 
have  been  conducted  on  all  scales  from  a  small  garden  plot  to 
a  five-acre  field.  The  various  types  of  spraying  apparatus  have 
been  tried  to  determine  their  merits  and  demerits.  The  number 
of  sprayings  in  each  case  has  been  reduced  to  the  minimum, 
because  it  was  felt  that  a  maximum  number  of  treatments  did 
not  meet  with  favor  among  growers  generally.  Most  of  the 
treatments,  however,  were  made  very  thorough,  for  upon  this 
thoroughness  and  the  proper  time  of  application  largely  depends 
the  success  of  spraying.  Bordeaux  mixture  (four  pounds  lime, 
four  pounds  copper  sulphate,  and  forty  to  fifty  gallons  water) 
was  used  in  all  cases,  with  the  addition,  when  needed,  of  Paris 
green  for  the  potato  beetle.  The  check  plants  were  also  usually 
sprayed  once  or  twice  with  Paris'  green.  In  making  the 
Bordeaux,  the  lime  was  slaked  in  a  small  amount  of  water  and 
then  strained  into  a  barrel  about  half  filled  with  water.  The 
copper  sulphate  (kept  in  stock  solution  of  one  pound  to  one 
gallon  of  water)  was  poured  into  another  barrel,  about  half 
filled  with  water.  The  half-barrel  of  copper  sulphate  solution 
was  then  poured  into  the  half-barrel  of  the  lime  water,  stirring 
the  mixture  as  this  was  done. 

No  direction  was  assumed  of  the  sprayed  fields  as  to  their 
culture,  fertilization,  etc.,  and  these  conditions  varied  consid- 
erably in  the  different  experiments.  In  testing  the  yields  it  was 
desired  to  determine  how  much  more  or  less  the  sprayed  plats 
gave  over  those  unsprayed  in  number  and  weight  of  tubers  and 
the  amount  of  rot  in  each.  These  tests  were  always  made  from 
the  same  measured  lengths  of  the  sprayed  and  unsprayed  rows, 
practically  side  by  side,  and  from  at  least  two  places  in  the  field. 
This  was  to  eliminate,  as  far  as  possible,  any  other  influence 
beside  the  spraying  that  might  affect  the  yields. 

Spraying  Experiments  in  ipo2. 

General  Notes.  This  year  the  blight  appeared  suddenly  in 
July  and  a  number  of  the  fields  were  ruined  by  it  before  the  end 
of  the  month.      (See  Plate  XXXII,  b.)       The  weather  during 


370         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

July  and  August  was  of  the  kind  especially  fitted  to  develop 
blight,  being-  cold,  rainy  and  foggy,  often  several  days  occurring 
together  with  little  or  no  sunshine.  By  the  middle  of  August 
there  were  few  green  potato  fields  in  the  state.  For  example, 
on  August  26,  while  riding  on  the  train  from  Unionville  to 
New  Haven,  there  were  counted  about  sixty  potato  fields,  and 
in  all  of  these  the  vines  were  entirely  dead,  excepting  three  or 
four,  where  the  vines  were  still  partially  green.  Except  for  the 
blight,  the  fields  of  late  potatoes  should  have  lived  until  killed 
by  the  frost,  which  this  year,  according  to  the  weather  bureau 
at  New  Haven,  did  not  occur  until  October  lo  and  October  22. 
Little  rot  developed  in  the  tubers,  the  injury  being  thus  largely 
confined  to  this  very  premature  death  of  the  vines. 

Exp.  I,  in  Ogden  field  zvith  late  potatoes.  This  field,  of 
about  half  an  acre,  was  elevated,  stony  and  the  soil  naturally 
rather  poor,  but  it  was  well  dressed  with  artificial  fertilizers  and 
the  culture  was  fair.  The  potato  vines  did  not  cover  the 
ground  so  densely  as  they  often  do  in  richer,  moist  soil,  so  it 
was  easier  to  protect  this  field  against  blight  than  one  of  rank 
growth.  The  first  spraying,  July  30,  was  made  just  after  a 
small  amount  of  blight  appeared  in  the  field.  This  application 
was  somewhat  tardy,  about  ten  days,  but  it  made  less  difference 
in  this  field  than  it  would  have  made  in  one  of  luxuriant  vege- 
tation. The  second  and  third  treatments  were  made  on  August 
5  and  August  23,  and  on  the  latter  date  there  was  evident  differ- 
ence between  the  sprayed  and  unsprayed  parts  in  the  injury 
from  blight.  On  September  2  the  unsprayed  plants  were  nearly 
all  dead,  while  the  sprayed  plants  were  mostly  alive,  being  the 
only  green  field  in  the  vicinity.  At  the  time  of  digging,  Sep- 
tember 25,  forty-two  of  the  two  hundred  and  twenty  sprayed 
plants  reported  in  Table  I  were  still  partially  green.  Plate 
XXXVI,  a-b,  shows  the  condition  of  sprayed  and  unsprayed 
plants  on  September  16.  The  spraying  was  done  with  an  ordi- 
nary barrel  pump  carried  on  a  light  spring  wagon.  One  man 
drove  and  pumped  and  one  man  sprayed  about  six  rows,  using 
a  twenty-five- foot  hose  with  a  single  nozzle.  The  wagon  reach 
was  about  six  inches  too  narrow  for  straddling  two  rows  per- 
fectly, so  the  vines  were  run  over  somewhat.  This  caused  little 
permanent  injury,  much  less  than  is  ordinarily  supposed,  but 
by  planting  the  rows  at  the  right  distance  or  by  using  a  cart 


SPRAYING  FOR  POTATO  BLIGHT. 


;7i 


having  the  right  gauge  this  trouble  can  be  largely  avoided. 
The  results  of  the  spraying  are  given  in  detail  in  Table  I. 
This  shows  that  the  sprayed  plat  gave  an  increase  of  io8  per 
cent,  in  weight  of  tubers  over  the  unsprayed  plat  and  the 
increased  yield  was  evident  not  only  in  the  number  of  market- 
able tubers,  but  also  in  their  larger  size.  Neither  sprayed  or 
unsprayed  potatoes  rotted  at  all.  This  experiment  gave  the  best 
results  of  any  tried  during  the  three  years. 

Table  I  — Late  Potatoes,  Ogden  Field,  1902. 


Large  to  me- 

Medium to 

Total 

Very 

small 

Dug. 

dium  tubers. 

small  tubers. 

marketable. 

tubers. 

£ 

Treatment. 

.£3 

g 

|t.S 

J3 

e 

ili 

;yi 

P 

1^4 

& 

°z 

Z 

Z 

I^ 

z 

^ 

z 

Z 

!^ 

es 

Sprayed  July  30, 

Sept  25, 

August    5, 

equal 

220* 

512 

237 

871 

157 

138.3 

384 

296 

i4i 

2 

August  23. 

length 

in  each 

plat. 

Unsprayed. 

IQ7* 

264 

io6f 

479 

78I 

743 

i85i 

248 

12 

5 

*  Planted  rather  unevenly  by  planter,  but  possibly  part  of  plants  in  unsprayed 
rows  destroyed  by  blight. 


E.rp.  2,  in  Neshit  field  after  blight  started.  These  potatoes 
were  on  rather  rich  lowland  and  the  vines  were  very  luxuriant, 
entirely  covering  the  ground.  When  first  sprayed,  the  mildew 
was  well  scattered  through  the  field  (not  consipcuous,  except  in 
a  few  scattered  patches,  where  the  plants  were  plainly  injured), 
and  all  the  conditions  were  favorable  to  rapid  advance  of  the 
blight  with  the  proper  weather.  The  experiment  was  under- 
taken to  determine  if  in  a  field  of  this  character  spraying  would 
be  of  any  value  when  tardily  applied.  The  first  treatment  was 
made  August  4  on  a  small  part  of  the  potatoes  on  either  side  of 
a  roadway,  spraying  in  as  far  as  could  be  reached  with  the 
twenty-five-foot  hose.  Favorable  blight  weather  followed  the 
spraying-,  and  when  examined  again  on  August  13  those  sprayed 
on  one  side  of  the  roadway  were  little  or  no  better  than  those 
unsprayed,  as  both  were  badly  blighted.  The  potatoes  on  the 
other  side  of  the  roadway  were  apparently  of  a  later  planting 
and  were  still  green,  though  severely  injured  by  the  blight,  and 


372         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

these  were  given  a  second  treatment.  These  two  sprayings, 
however,  failed  to  check  the  progress  of  the  bhght,  and  when 
finally  examined  on  September  15  the  only  difference  seen 
between  the  sprayed  and  unsprayed  parts  was  an  occasional 
partially  green  plant  in  the  sprayed  plat.  The  rest  of  the  field 
was  entirely  dead.  As  no  influence  on  the  yield  was  expected 
from  these  results,  this  was  not  determined.  We  conclude  from 
this  experiment  that  it  is  useless  to  begin  spraying  in  a  field  with 
luxuriant  foliage  after  the  blight  has  become  well  established 
and  the  season  is  favorable  for  its  development. 

Spraying  Experiments  in  ipo^. 

General  Notes.  This  season  was  also  wet,  though  not  so 
cold  or  damp  as  the  preceding.  The  blight  appeared  consid- 
erably later ;  the  very  first  found  by  the  writer  was  on  August 
8.  From  this  time  on  it  spread  through  the  fields,  gradually 
killing  the  leaves  until  August  24  to  31,  when  in  a  period  of 
weather  favorable  to  blight  all  of  the  fields  where  it  had  a  foot- 
hold were  quickly  ruined.  The  possible  yield  was  not  cut  down 
so  much  as  the  year  before  by  premature  death  of  the  vines,  but 
the  rot  in  the  tubers  was  much  more  serious.  These  did  not 
begin  to  rot,  with  the  late  varieties  at  least,  until  the  plants  were 
killed  by  the  blight ;  yet  from  an  examination  of  the  tubers  the 
writer  could  not  find  the  blight  fungus  as  the  agent  of  the  rot. 
Most  of  the  tubers  examined  began  to  decay  at  the  stem  end  and 
the  rot  seemed  to  be  caused  by  bacteria  and  the  Fusarium 
fungus.  The  largest  tubers  suffered  the  most.  By  killing  the 
green  vines  the  blight  fungus  probably  (indirectly)  was  respon- 
sible for  starting  these  troubles. 

Most  of  the  spraying  this  year  was  made  or  started  with 
geared  spraying  carts  in  order  to  test  the  efficiency  of  this  kind  of 
an  apparatus.  ( See  Plate  XXXV. )  Spraying  by  hand  requires 
more  time  and  men  than  these  machines,  where  the  horse,  at  the 
same  time  he  is  pulling  the  apparatus  through  the  field,  is  pump- 
ing (by  means  of  gearing  attached  to.  the  wheels)  the  Bordeaux 
from  stationary  nozzles  that  project  over  the  potato  rows. 
Only  one  man  is  needed,  and  he  drives,  seated  on  the  cart.  Two 
machines  were  used  that  seemed  to  be  as  well  fitted  for  the  work 
as  anv.  Our  experience  with  these  machines,  and  our  observa- 
tion and  information  concerning  others,  leads  us  to  conclude 


SPRAYING   FOR    POTATO   BLIGHT.  373 

that  such  machines  are  not  to  be  recommended  for  applying 
Bordeaux  mixture  against  potato  bHght.  There  is  need,  how- 
ever, of  some  cheap  machine  that  will  do  the  spraying  more 
rapidly  and  cheaply,  and  yet  about  as  thoroughly  as  can  be  done 
by  hand.  One  of  the  machines  tried  had  single  nozzles  for 
covering  four  rows,  while  the  other  had  double  nozzles.  Neither 
machine  could  place  sufficient  spray,  well  distributed,  on  the 
vines,  even  by  going  over  the  potatoes  two  and  three  times,  at 
the  same  spraying.  Usually  the  Bordeaux  showed  as  a  streak 
of  blue  on  the  tops  of  the  full-grown  vines.  The  use  of  sta- 
tionary nozzles,  even  with  two  to  a  row  and  a  level  and  evenly 
planted  field  for  spraying,  occasionally  caused  parts  of  a  row  to 
be  missed.  The  slower  the  geared  machine  is  driven  the  less 
the  power,  and  yet  it  is  desirable  to  go  slow  in  order  to  place 
more  spray  on  the  vines.  Even  at  their  best,  these  machines 
used  only  about  a  barrel  of  the  spray  to  an  acre  and  a  half, 
whereas  two  or  three  barrels  per  acre  is  needed  to  thoroughly 
protect  the  mature  vines. 

The  apparatus  shown  in  Plate  XXXIV,  b,  is  a  type  often 
used.  In  this  case  the  stationary  nozzles  are  attached  to  the 
end  of  an  ordinary  cart  carrying  a  barrel  pump,  and  the  pump- 
ing is  done  by  hand.  This,  too,  has  some  of  the  objections  of 
the  geared  machines.  By  very  slow  driving,  however,  more 
spray  can  be  placed  on  the  vines,  but  because  of  the  stationary 
nozzles  it  will  not  be  done  very  thoroughly  or  evenly.  In  this 
particular  apparatus  better  work  would  have  been  done  if  the 
pump  had  been  stronger.  It  was  not  powerful  enough  to 
readily  supply  the  eight  nozzles  used. 

By  far  the  most  satisfactory  type  of  spraying  outfit  for 
thoroughness  of  work  is  that  shown  in  Plate  XXXIV,  a.  This 
is  merely  a  two-wheeled  cart,  of  sufficient  reach  to  straddle  two 
rows  of  the  potatoes,  which  carries  an  ordinary  barrel  pump  and 
a  man  to  pump  and  drive.  Two  men  follow  the  cart,  each 
using  a  twenty-five- foot  hose  with  a  single  nozzle,  and  they  each 
spray  three  rows  without  moving  from  the  row,  in  which  they 
travel  backward.  The  man  drives  the  length  of  the  hose  and 
the  men  spray  their  rows  up  to  the  cart,  which  then  moves  on 
again.  In  this  way  the  ground  can  be  gone  over  fairly  quickly 
and  the  spraying  can  be  done  as  thoroughly  as  desired.  Two 
nozzles  to  a  hose  seem  to  be  little  better  than  one  and  waste 
29 


374         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

more  of  the  material.  Where  onty  two  men  are  available  for 
the  work,  only  one  need  be  used  for  spraying.  Each  hose  should 
be  fitted  with  a  cock  at  the  nozzle  and  a  holder  for  inserting  a 
short  pole  for  directing  the  spray.  The  chief  objections  against 
this  method  of  spraying  are  that  it  requires  an  extra  man  or  two, 
and  its  slowness ;  but,  taken  altogether,  it  is  the  best  way  known 
to  the  writer  for  spraying  any  considerable  area  thoroughly. 

Exp.  J,  in  Farnham  field  with  late  potatoes.  This  level  field, 
of  about  six  acres,  has  a  rich  but  slightly  sandy  soil.  The  culti- 
vation and  fertilization  were  good.  The  first  blight  was  found 
in  the  field  August  8,  or  after  the  first  two  sprayings  had  been 
made.  These  treatments  were  made  with  the  geared  power 
sprayer,  but  this  worked  so  unsatisfactorily  that  six  rows  (plat 
A,  see  Table  II)  next  the  four  unsprayed  rows  were  sprayed  on 
August  8  and  August  24  by  hand,  as  shown  in  Plate  XXXIV,  a. 
On  August  24  the  blight  had  made  such  progress  in  the  main 
part  of  the  field  sprayed  by  the  geared  machine  that  part  of  this 
was  sprayed  more  thoroughly  by  hand,  but  this  was  too  late  to 
materially  check  the  advance  of  the  blight.  On  this  date  the 
thoroughly  sprayed  six  rows,  plat  A,  were  in  fair  condition, 
while  the  unsprayed  rows  were  two-thirds  gone  with  the  blight. 
On  September  3  the  unsprayed  rows  were  entirely  dead ;  the 
imperfectly  sprayed  main  field,  plat  B,  was  about  as  badly  gone ; 
v^hile  the  more  thoroughly  sprayed  plat  A  was  still  green,  having 
only  about  half  the  foliage  destroyed.  (See  Plate  XXXVII.) 
The  yield,  as  tested  on  September  4,  gave  the  more  perfectly 
sprayed  plat  A  59  per  cent,  greater  yield  by  weight  than  the 
unsprayed  rows  next  to  it,  while  the  imperfectly  sprayed  plat  B, 
which  was  tested  quite  removed  from  the  check  unsprayed  rows, 
gave  42  per  cent,  greater  yield.  At  this  date  little  rot  had  devel- 
oped in  the  field.  As  the  vines  in  plat  A  were  still  partially  green 
at  this  time,  a  second  test  of  this  and  the  check  rows  was  made 
on  September  25,  after  all  the  vines  were  dead.  This  test  was 
made  in  rows  side  by  side  with  the  first.  It  showed  that  while 
plat  A  had  made  some  increase  in  weight  and  number  of  mar- 
ketable tubers  during  this  interval,  this  was  completely  offset 
by  the  rot  that  had  developed.  The  unsprayed  rows,  however, 
being  entirely  dead,  had  made  no  increase  and  had  suffered 
more  severely  through  rot.  So  on  the  second  digging  the 
sprayed  plat  A  showed  91  per  cent,  increase  in  weight  over  the 


SPRAYING  FOR  POTATO  BLIGHT. 


375 


unsprayed.  This  experiment  indicates  that  the  rot  starts  soon 
after  the  death  of  the  vines,  usually  in  a  week  or  so,  as  was 
shown  in  the  digging  of  the  main  field. 

Table  II. — Late  Potatoes,  Farnham  Field,  1903. 


Large  to 

Medium  to 
small  tubers. 

Total 
marketable. 

Very  small 
tubers. 

Rotten 
tubers. 

Dug 

(200  fe 

-t). 

c 
"H, 

Treatment. 

g 
3 

Mm 

B 

z 

u 

B 

3 

s 
z 

M„- 

6 
Z 

'5-0 

(A)      Sprayed  ; 
July  10,  Aug.   I, 
Aug.  8,  Aug.  24. 

Sept. 
Sept. 

4 

25 

129 
119 

151 

53 

72 

27i 

563 
651 

i5oi 

714 

704 

187 

178 

125 
172 

7 
8f 

0 

50 

14 

Unsprayed,  or 

Sept. 

4 

126 

29 

13 

618 

I04i 

647 

ii7i 

123 

6i 

5 

Check. 

Sept. 

25 

127 

II 

6 

369 

82 

380 

93 

143 

9 

104 

25 

(B)    Imperfect- 
ly sprayed  :  July 
10,  Aug.  r,  Aug. 

Sept. 

4 

130 

140 

67 

444 

100 

574 

167 

62 

4 

4 

24. 

E;!:/).  ^,  in  Farnham  field  with  late  variety  planted  very  late. 
This  was  in  the  same  field  reported  in  experiment  3,  but  the 
potatoes  were  not  planted  until  about  the  middle  of  June. 
The  experiment  was  to  determine  if  such  late  planting  on  land 
used  earlier  in  the  season  for  other  crops  was  feasible  if  the 
potatoes  were  sprayed  to  ward  oif  the  blight,  which  might  other- 
wise carry  them  off  before  the  tubers  were  of  marketable  size. 
Unfortunately  only  two  treatments  were  made.  Doubtless  three 
would  have  given  better  results,  especially  if  the  first  had  been 
made  a  little  earlier.  At  the  time  of  the  first  spraying,  August 
8,  a  little  blight  was  found  on  these  plants,  but  it  was  not  nearly 
so  abundant  as  in  the  unsprayed  part  of  the  earlier  planted 
potatoes.  On  August  24,  at  the  time  of  the  second  spraying, 
the  fungus  was  common  in  the  check  rows  of  the  unsprayed 
late-planted  potatoes,  but  still  was  not  nearly  so  abundant  as  in 
the  unsprayed  early  planted  potatoes.  This  confirms  DeBary's 
statement  that  blight  generally  seems  to  develop  most  promi- 
nently in  a  field  when  the  vines  are  in  their  prime  of  development. 
On  September  3  the  unsprayed  rows  were  very  nearly  gone  with 


376         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

the  blight,  while  the  sprayed  rows  still  retained  half  of  their 
foliage.  The  sprayed  plat  was  dug  September  25,  when  the  yield 
was  found  to  be  a  little  greater  and  the  rot  a  little  less  than  in  the 
unsprayed  plat  of  the  early  planted  portions  of  the  field.  It  was 
not  possible  to  compare  it  with  its  proper  check,  since  this  had 
been  dug  by  accident  a  few  days  before,  but  the  man  in  charge 
said  that  these  unsprayed  rows  had  yielded  very  poorly.  It 
would  seem  from  this  experiment,  then,  that  where  it  is  very 
desirable  to  use  a  field  for  another  crop  until  the  middle  of  June, 
a  moderate  yield  of  potatoes  can  be  secured  from  it  afterward  if 
these  are  thoroughly  sprayed  three  times  to  ward  off  the  blight. 
Exp.  5,  in  Ogden  field  with  early  and  late  potatoes.  This 
field  contained  about  one  acre  and  a  half  of  rather  level  and 
medium  rich  land.  The  day  before  planting  the  potatoes  the 
green  rye  on  the  field  was  plowed  under.  Dry  weather  fol- 
lowed, so  that  the  potatoes  were  a  long  time  coming  up,  and 
a  very  uneven  stand  was  made,  as  many  of  the  plants  never 
came  up  or  were  rotted  ofif  below  the  ground  by  a  bacterial  rot. 
Without  much  question,  the  humus  of  the  decaying  rye  had 
much  to  do  with  this  stem  rot  and  the  severe  rot  of  the  tubers 
that  developed  later.  The  field  was  very  poorly  cultivated  and 
became  very  weedy.  All  of  these  conditions  were  against  the 
potatoes.  The  vines  were  sprayed  three  times  (July  5,  August 
II,  September  i),  twice  with  the  geared  spraying  machines 
and  once  with  the  stationary  nozzle  outfit  shown  on  Plate 
XXXIV,  b.  It  was  impossible  with  either  of  these  appliances 
to  properly  cover  the  foliage,  even  by  going  over  the  field  two 
and  three  times  each  spraying.  Consequently  the  spraying  was 
done  very  imperfectly.  August  11,  at  the  time  of  the  second 
spraying,  blight  was  first  noticed  in  the  field,  being  most 
abundant  on  the  unsprayed  early  potatoes.  September  i  the 
blight  was  quite  prevalent  in  the  field  and  with  but  slight  dififer- 
ence  in  favor  of  the  sprayed  parts.  When  dug  on  September 
21  all  of  the  vines  had  been  dead  for  some  time.  The  rot, 
which  developed  very  badly,  was  largely  a  soft  bacterial  rot.  A 
field  nearby  suffered  very  little  from  rot.  The  sprayed  plat  of 
the  late  variety,  which  constituted  most  of  the  field,  gave  20  per 
cent,  less  yield  by  weight  than  did  its  unsprayed  plat.  This 
was  the  only  experiment  during  the  three  years  in  which  a 
smaller  yield  was  got  from  a  sprayed  than  from  an  unsprayed 


SPRAYING   FOR    POTATO    BLIGHT. 


377 


plat,  but  even  here  the  yield  was  originally  greater  in  the  sprayed 
plat,  but  lost  through  more  severe  rotting  of  the  tubers.  The 
early  variety,  however,  gave  an  increase  of  loo  per  cent,  for  the 
sprayed  over  the  unsprayed  vines.  Because  of  the  imperfect 
spraying  and  the  development  of  severe  rot,  probably  due  to 
plowing  under  the  green  rye,  the  experiment  was  not  very 
satisfactory.     See  Table  IIL  for  details. 


Table  III. — Late  and  Early  Potatoes,  Ogden  Field,  1903. 


Dug. 

(loofert.) 

a, 

S 
Z, 

Large  to 
medium 
tubers. 

Medium  to 
small 
tubers. 

Total 
marketable. 

Very  small 
tubers. 

Rotten 
tubers. 

Treatment. 

C 

E 
Z 

s 
1 

1" 

E 
1 

u 

s 

3 

A.   Late  variety. 

- 

Imperfectly 

sprayed  : 
July  15,  Aug.  II, 
Sept.  I. 

Sept.  21 

64 

6 

3 

92 

17 

98 

20 

96 

4 

165 

22 

Unsprayed  : 

Sept.  21 

64 

2 

I 

131 

23 

133 

24 

188 

9 

81 

II>^ 

B.  Ea7'ly  variety. 

Imperfectly 

sprayed  : 
July  15,  Aug.  II, 
Sept.  I. 

Sept.  21 

60 

2 

^% 

223 

35 

225 

36>^ 

126 

6 

74 

10 

Unsprayed  : 

Sept.  21 

55 

0 

0 

92 

18 

92 

18 

73 

4 

39 

6 

Spraying  Experiments  in  1^04. 

General  Notes.  This  year  was  drier  and  warmer  than  either 
of  the  two  preceding  years  and  did  not  develop  special  blight 
weather  during  July  or  August.  The  very  first  blight  seen  was 
on  August  3,  but  September  found  most  of  the  late  potato  fields 
still  green,  and  it  was  during  the  moist  weather  of  this  month 
that  most  of  the  injury  to  the  foliage  was  done.  Coming  so 
late  in  the  season,  however,  this  injury  would  have  been  insig- 
nificant, and  a  large  crop  would  have  been  harvested,  but  for 
the  fact  that  this  late  blighting  served  to  supply  the  spores  that 
during  the  moist  weather  of  September  and  October  started  a 
very  serious  and  widespread  rot  of  the  tubers.     Unlike  the  pre- 


3/8         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

ceding  year,  this  rot  could  be  directly  traced  in  its  beginning 
to  the  blight  fungus.  The  rot  started  at  any  place  on  the  tubers, 
attacking  small  as  well  as  large  ones  when  severe,  and  showed 
the  characteristic  sunken  areas  with  reddish  brown  discolora- 
tion of  the  superficial  tissues  beneath.  There  is  little  doubt, 
however,  that  after  the  blight  fungus  started  the  trouble,  bac- 
teria were  often  responsible  for  extending  it,  even  outstripping 
the  blight  fungus  in  their  progress  and  injury. 

Exp.  6,  in  Farnham  field  with  early  potatoes  and  early  spray- 
ing. This  was  a  level,  rather  low  field  of  rich  but  slightly 
sandy  soil,  and  was  well  fertilized  and  thoroughly  cultivated 
during  the  season.  The  aim  of  the  experiment  was  to  deter- 
mine if  spraying  would  prove  profitable  in  a  field  of  early 
potatoes  that  were  to  be  dug  and  sold,  at  least  in  part,  as  soon 
as  they  were  of  marketable  size.  As  the  earliest  potatoes  are 
often  dug  for  the  market  about  the  time  that  the  blight  appears, 
it  was  not  expected  that  benefit  would  result  so  much  from 
preventing  blight  as  it  would  from  better  protection  against 
potato  bugs  and  flea  beetles,  and  from  the  stimulation  that 
Bordeaux  mixture  seems  to  give  potatoes  even  when  free  from 
fungus  attack.  Blight  was  so  late  in  appearing  that  it  was  not 
found  in  this  field  even  on  the  unsprayed  vines.  The  gain 
from  spraying,  therefore,  resulted  entirely  from  better  protec- 
tion of  the  foliage  from  insect  attack  and  from  the  stimulative 
action  of  the  Bordeaux  mixture.  The  spraying  was  made  with 
the  barrel  pump  mounted  in  a  cart  and  was  done  very  thor- 
oughly. The  first  treatment  was  given  June  17,  and  the  second, 
on  July  7,  was  made  on  only  part  of  the  field  next  the  unsprayed 
rows.  The  difiference  in  appearance  of  foliage  between  the 
sprayed  and  unsprayed  plats  on  July  7  was  marked.  In  the 
plats  sprayed  with  Bordeaux  mixture  one  pound  of  Paris  green 
per  barrel  was  used,  and  as  the  foliage  was  thoroughly  covered 
and  the  sediment  adhered  through  the  season,  this  protected 
the  vines  completely  from  the  potato  beetles.  The  check  rows 
also  had  been  sprayed  twice  with  Paris  green  only  (by  the 
owner),  with  a  geared  spraying  machine.  The  spraying  by 
this  method  was  imperfectly  done  and  there  was  nothing  to  keep 
the  poison  from  washing  off  by  rains,  so  these  vines  suffered 
severely  from  attack  by  the  bugs,  and  as  no  lime  was  used  with 
the  Paris  green  this  also  burned  the  foliage  considerably.     The 


SPRAYING  FOR  POTATO  BLIGHT. 


379 


•first  digging  was  made  on  July  20,  as  soon  as  the  tubers  were 
ready  for  market.  Despite  the  injury  from  the  bugs  and  Paris 
green  burn,  the  unsprayed  plat  at  this  digging  yielded  about  as 
well  as  either  the  plat  sprayed  once,  which  gave  only  3  per  cent, 
greater  yield  by  weight,  or  the  plat  sprayed  twice,  which  gave 
5  per  cent,  greater  yield.  As  the  sprayed  plants  at  this  time 
were  still  in  their  prime  and  the  unsprayed  plants  nearly  dead, 
a  second  test  was  made  August  5,  after  all  the  plants  were  about 
gone.  The  test  showed  an  increase  of  8  per  cent,  in  those 
sprayed  once  and  of  17  per  cent,  of  those  sprayed  twice  over 
the  unsprayed  plat.  There  was  no  loss  from  rot.  This  experi- 
ment indicates  that,  where  early  potatoes  are  dug  as  soon  as 
marketable,  spraying  with  Bordeaux  mixture  does  not  pay,  but 
when  these  potatoes  are  left  until  the  vines  are  entirely  dead 
the  spraying  will  be  of  greater  value,  especially  if  early  blight 
has  been  injurious  or  the  late  blight  appears  before  the  end  of 
their  season.  There  is  no  doubt  that  Paris  green  used  in  Bor- 
deaux is  more  effective  in  repelling  attack  of  the  potato  beetle 
and  even  the  flea  beetle  than  when  used  alone,  and  there  is  then 
absolutely  no  danger  of  burning  the  foliage.  It  is  the  extra 
cost  of  applying  the  Bordeaux  mixture,  especially  if  labor  is 
an  important  factor,  that  largely  offsets  its  benefits  in  spraying 
early  potatoes,  unless  these  are  severely  injured  by  preventable 
fungus  attack.     For  details  of  experiment,  see  Table  IV. 

Table  IV.     Early  Potatoes^  in  Farnham  Field^  1904. 


Dug. 

(200  ft.) 

c 
"3. 

E 
a 

2; 

Large 
dium 

to  me- 
ubers. 

Medium  to 
small  tubers. 

Total 
marketable. 

Very  small 
tubers. 

u 

Treatment. 

u 

S 
3 

2 

> 

S 
3 
2 

.a 
B 

Z 

43 
S 

z 

J5 

3 

C 

0 

Pi 

Sprayed  once,  June  17. 

July  20 
Aug.  5 

146 

4 
22 

3 
13 

1007 
1022 

I97K 

206 

lOII 
1044 

200^ 
219 

319 
356 

I2>^ 
15 

0 

2 

Sprayed    twice,    June 
17,  July  7. 

July  20 
Aug.  5 

148 

4 

34 

2^ 
20 

III4 
1034 

210 

224>^ 

III8 
1068 

212'/^. 
244  ^^ 

294 

400 

13 
16 

0 
2 

Unsprayed. 

July  20 
Aug.  5 

148 

17 
20 

12 

998 

184 
1 96 

932 
IOI8 

195'/^ 
208 

387 

334 

15 
15 

0 
0 

380         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

Exp.  Y,  in  Farnham  field  with  late  potatoes.  This  was  an 
acre  field  of  about  the  same  character  as  the  preceding,  except 
the  cultivation  given  the  potatoes  was  very  poor.  As  a  result 
the  field  became  very  weedy,  which  somewhat  hindered  spray- 
ing, and  the  tubers  were  formed  so  close  to  the  ground  that  they 
were  easily  reached  by  the  spores  of  the  blight  fu7tgus  and  so 
suffered  severely  from  rot.  All  the  potatoes  except  three  check 
rows  were  sprayed  four  times,  using  the  barrel  pump  mounted 
on  a  cart,  namely,  on  July  7,  July  20,  August  5  and  August  20. 
As  the  potatoes  were  planted  very  late,  the  first  spraying  was 
made  when  they  were  only  eight  to  ten  inches  high.  The  vines 
were  severely  attacked  by  potato  bugs,  especially  the  check  rows, 
though  these  were  sprayed  twice  by  a  geared  machine  with  Paris 
green  only.  On  August  5,  or  at  the  time  of  the  third  spraying, 
no  blight  was  found  in  the  field.  The  writer  was  not  present 
at  the  fourth  spraying,  but  when  examined  again  on  September 
8  the  unsprayed  vines  were  all  dead,  though  the  stems  were  still 
green,  having  apparently  been  injured  chiefly  by  the  potato 
bugs.  The  sprayed  vines  were  still  green,  but  now  showed 
many  blighted  leaves  scattered  through  the  field.  The  fungi- 
cide at  this  time  was  almost  all  off  the  foliage  and  the  wet  Sep- 
tember weather  that  followed  rapidly  developed  the  blight,  so 
that  at  the  end  of  the  next  ten  days  the  vines  were  mostly  dead. 
The  effect  of  this  delayed  appearance  of  the  blight  was  to 
develop  a  serious  rot  of  the  tubers,  especially  in  the  sprayed  plat, 
for  the  vines  in  the  unsprayed  plat  had  largely  died  before  the 
appearance  of  the  blight.  If  the  potatoes  had  been  properly 
cultivated,  and  especially  if  the  tubers  had  been  buried  deeper 
under  the  soil  by  some  system  of  ridge  culture,  it  does  not  seem 
likely  that  the  rot  would  have  developed  nearly  so  badly.  The 
potatoes  were  not  dug  for  the  test  until  October  4,  when  it  was 
found  the  rot  had  become  very  serious,  especially  in  the  center 
of  the  field,  which  was  slightly  lower  and  probably  more  moist. 
The  rot  apparently  had  developed  recently,  as  the  lower  end  of 
the  field  when  dug  a  week  or  ten  days  before  revealed  little 
rot.  The  test  showed  that  while  the  sprayed  plat  developed 
much  more  rot  (half  the  tubers  were  rotted)  than  the  unsprayed 
plat,  it  still  gave  a  yield  of  sound  tubers  73  per  cent,  greater  in 
weight.     For  details,  see  Table  V. 


SPRAYING   FOR    POTATO   BLIGHT.  38 1 

Table  V.    Late  Potatoes  planted  late,  in  Farnham  Field,  1904. 


Dug. 
(200  it.) 

Number 
plants. 

Large  to 
medium 
tubers. 

Medium  to 
small 
tubers. 

Total 
marketable. 

Very 
small 
tubers. 

Rotten 
tubers. 

Treatment. 

u 

E 

1 

1 

£ 

1 

.£3 

e 

1 

e 

s 

.5? 
1 

J3 

a 

XI 

Sprayed,    July 
7,    July     20, 
Aug.  5,  Aug. 
20. 

Oct.  4 

Not 
Recorded 

5 

4 

367 

68>^ 

372 

72i 

190 

7i 

370 

82 

Unsprayed. 

Oct.  4 

3 

2 

265 

40 

268 

42 

441 

14 

44 

4 

^^.r/j.  5,  w  Clinton  garden  with  early  and  late  potatoes.  This 
garden  is  in  an  isolated  spot,  well  shut  off  by  trees  and  hills 
from  any  other  garden  or  field,  and  has  been  in  use  only  two 
years.  Whether  this  accounts  for  it  or  not,  it  is  a  fact  that  dur- 
ing these  two  years  blight  has  been  slower  in  appearing  here  and 
less  injurious  than  in  almost  any  place  observed  by  the  writer. 
The  location  is  rather  low,  and  moist  at  one  end,  and  the  soil 
is  derived  largely  from  red  rock,  but  with  plenty  of  humus. 
These  potatoes  were  sprayed  with  one  of  the  compressed  air 
knapsack  sprayers,  which  work  fairly  well  when  comparatively 
small  patches  are  to  be  sprayed.  The  blight  did  little  damage 
to  the  early  potatoes  and  developed  in  the  late  abundantly  only 

Table  VI.     Late  and  Early  Potatoes,  in  Clinton  Garden,  1904. 


Dug. 

(50  ft.) 

c 

"3. 
\^ 

s 

Large  to 
medium 
tubers. 

Medium  to 
small 
tubers. 

Total 
marketable. 

Very  small 
tubers. 

Rotten 
tubers. 

Treatment. 

J3 
S 

■   3 

6 
3 
Z 

J3 

B 

3 

a 

3 
z 

Mm 
"Exi 

a 
3 
z 

'53x1 

A.     Early  Potatoes. 
Sprayed  June  23, 

July  2 

Unsprayed 

Oct.  6 
Oct.  6 

33 

33 

4 
0 

2i 
0 

184 

38i 
29 

192 

150 

41 
29 

30 
53 

2i 

3 
17- 

f 

3f 

B.     Late  Potatoes. 
Sprayed    July    2, 

Jiily  27 

Unsprayed 

Oct.  6 
Oct.  6 

32 
36 

11 
II 

8 
8 

161 
163 

47 
42 

172 
174 

55 
50 

27 
27 

li 

7 
6 

2^ 
f 

382         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O4. 

at  the  very  end  of  the  season.  These  latter  should  have  had  one 
or  two  more  sprayings.  There  was  very  little  rot,  probably 
because  the  tubers  were  well  covered  by  earth  through  ridge 
culture;  the  patch  was  a  decided  contrast,  in  this  respect,  with 
the  Farnham  field,  Exp.  7,  which  was  dug-  a  few  days  before. 
The  early  potatoes  gave  an  increase  of  41  per  cent.,  but  the  late 
only  10  per  cent,  over  their  unsprayed  rows. 

Summary  and  Conclusions. 

The  blight  fungus,  Phytophthora  infestans,  while  by  far  the 
worst  fungous  pest  of  the  potato  in  Connecticut,  is  often  held 
responsible  for  any  serious  injury  to  the  vines  or  rot  of  the 
tubers.  The  Rhizoctonia  fungus,  the  early  leaf  blight,  the 
Fusarium  fungus,  the  bacterial  stem  rot,  the  wet  bacterial  rot 
of  tubers  and  the  well  known  scab  are  all  parasitic  agents  at 
work  in  our  potato  fields  and  cause  more  or  less  injury.  Con- 
siderable burning  of  the  leaves  is  also  done  by  the  careless  use 
of  Paris  green.  In  dry  seasons,  due  to  uncontrolled  loss  of 
moisture,  tip  burn  of  the  leaves  may  develop. 

During  the  three  seasons  1902,  1903,  1904,  which  were  years 
more  moist  than  the  average,  the  potatoes  in  this  state  suffered 
rather  severely  from  blight,  the  crops  being  cut  down  at  least 
25  per  cent.  In  1902  the  sudden  and  early  blighting  of  the 
vines  prevented  a  large  yield,  but  there  was  little  rot;  in  1903 
the  yield  was  affected  somewhat  by  the  blighting  of  the  vines, 
but  was  decreased  chiefly  by  bacterial  and  Fusarium  rots  of 
the  tubers  that  were  apparently  started  by  the  premature  death 
of  the  vines ;  while  in  1904  blight  was  so  late  in  developing 
that  it  did  little  injury  to  the  vines,  but  did  develop  a  serious 
rot  of  the  tubers  that  carried  off  a  large  percentage  of  the 
crop. 

Early  potatoes  suffer  very  much  less  from  blight,  especially 
in  limiting  the  life  of  the  vines,  than  the  late  varieties.  This, 
is  because  the  blight  often  appears  only  toward  the  end  of  their 
season  and  sometimes  not  until  they  are  entirely  gone.  It 
might  be  advocated,  then,  that  early  potatoes  should  largely 
supplant  the  late  varieties.  The  yield  from  the  late  varieties, 
however,  aside  from  serious  injury  from  blight,  is  considerably 
greater,  and  because  of  this,  and  probably  for  other  reasons,  the 
late  varieties  generally  seem  to  be  much  more  in  favor  with 


SPRAYING   FOR    POTATO   BLIGHT.  383 

growers.  Early  potatoes,  too,  are  not  exempt  from  serious 
troubles. 

There  is  no  doubt  that  the  character  of  the  season  is  the 
dominant  factor  in  determining  how  little  or  how  much  damage 
will  be  caused  by  blight.  Rainy  weather  in  July  and  August 
starts  the  fungus  in  the  fields,  and  if  there  then  comes  a  con- 
tinuous period  of  rainy,  cloudy  or  foggy  weather  the  foliage 
will  soon  be  destroyed.  Wet  weather  in  August  or  September 
following  the  blighting  of  the  vines  determines  largely  the 
amount  of  rot  that  develops  in  the  tubers. 

Besides  the  weather  conditions,  the  moisture  capacity  of  each 
field  or  portion  of  a  field  no  doubt  determines  largely  in  a  wet 
season  the  amount  of  rot  that  develops.  This  moisture  in  the 
soil  is  determined  largely  by  elevation,  drainage,  mechanical 
character  of  the  soil  and  its  humus  content.  Other  conditions 
heing  equal,  well-drained,  light,  sandy  soils  apparently  develop 
the  least  rot.  As  manure  adds  to  the  humus  of  the  soil  and  is 
a  carrier  of  certain  troubles,  as  scab,  etc.,  artificial  fertilizers, 
rather  than  manure,  should  be  used  on  the  land  the  year  it  is 
planted  with  potatoes. 

As  the  blight  fungus,  so  far  as  known,  carries  over  the  winter 
only  in  the  seed  potatoes,  the  first  step  in  lessening  the  disease 
should  be  with  the  selection  of  seed  as  free  as  possible  from 
this  and  any  other  fungus  disease,  as  scab,  Rhizoctonia,  etc. 
The  selection  of  even  perfect  seed  will  not  secure  freedom  from 
blight,  as  this  trouble  is  often  carried  from  one  field  to  another 
after  its  general  appearance ;  but  it  possibly  may  defer  the  time 
of  its  attack  and  lessen  the  injury. 

Thorough  cultivation  tends  to  conserve  the  moisture  of  the 
soil  in  a  dry  season  (when  there  is  little  danger  of  rot)  and  in  a 
wet  season  it  helps  to  keep  the  ground  from  becoming  wet  and 
soggy.  Ridging  the  rows  as  late  as  possible  in  July  holds  up 
the  vines  from  the  ground  and  thus  aids  in  a  quicker  evapora- 
tion of  moisture  from  the  foliage  and  ground,  and  in  so  doing 
aids  in  retarding  the  spread  of  the  blight.  It  also  covers  the 
tubers  deeper  in  the  soil  and  so  protects  them  better  from  the 
l)light  spores  that  fall  from  the  leaves.  Where  spraying  is 
practiced  it  also  makes  this  operation  easier.  The  objection  to 
ridging  is  that  in  a  dry  season  it  may  cause  the  plants  to  suffer 
for  lack  of  moisture. 


384         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I904. 

The  results  of  spraying  with  Bordeaux  mixture  vary  vyith 
different  seasons,  but  depend  largely  on  the  thoroughness  of 
the  treatments  and  their  application  at  the  proper  time.  It  is 
much  easier  to  secure  an  increased  yield  of  potatoes  from  spray- 
ing than  it  is  to  prevent  rot  in  these  afterward.  This  increased 
yield  varies  from  almost  nothing  to  sometimes  over  loo  per 
cent.,  and  the  rot  of  the  tubers  is  usually  less  in  the  sprayed  than 
in  the  unsprayed  fields.  An  average  gain  of  15  to  20  per  cent, 
should  be  had  in  order  to  pay  for  the  extra  cost  and  trouble  of 
spraying ;   any  gain  above  that  is  profit. 

When  late  potatoes  are  to  be  sprayed  for  blight,  the  writer 
advocates  three  or  four  thorough  applications,  the  first  to  be 
made  July  5  to  15,  according  to  the  weather,  and  the  final  one 
the  last  of  August  or  first  of  September.  Paris  green,  if 
needed,  can  be  used  in  the  Bordeaux,  half  a  pound  to  the  barrel. 
Two  to  three  barrels  of  the  mixture  should  be  used  per  acre  at 
each  spraying.  Aim  to  have  the  vines  thoroughly  protected 
with  the  fungicide  when  the  Ijlight  weather  appears. 

Geared  spraying  machines  are  rather  unsatisfactory  for  spray- 
ing Bordeaux  mixture,  since  they  cover  the  vines  very  imper- 
fectly with  the  spray.  If  used,  the  vines  should  be  gone  over 
two  or  three  times  each  spraying.  The  barrel  pump  mounted 
on  a  cart  that  can  straddle  two  rows  of  potatoes,  and  one  man 
to  drive  and  pump  and  one  or  two  men  to  follow  on  foot,  each 
with  a  twenty-five-foot  hose,  treating  three  or  four  rows,  is 
the  most  thorough  way  of  spraying  a  field.  (See  Plate 
XXXIV,  a.) 

When  there  is  danger  from  rot  the  potatoes  should  be  dug 
only  in  bright  weather,  after  the  dew  is  off  the  vines,  and  they 
should  be  spread  out  to  dry  off  and  be  gathered  up  before 
evening.  When  the  vines  are  blighting  it  is  difficult  to  dig  the 
potatoes  without  the  spores  coming  in  contact  with  the  tubers, 
so  some  advocate  leaving  the  potatoes  in  the  ground  at  least 
ten  days  or  two  weeks  after  the  death  of  the  vines.  Potatoes 
should  be  dried  as  thoroughly  as  possible  before  storage  and 
should  finally  be  stored  in  a  dry,  cool  place.  A  little  dry  air- 
slaked  lime  dusted  over  them  no  doubt  aids  somewhat  in  their 
drying  out. 


PLATE  XXXII. 


a.   Green  leaves  showing  early  stage  of  blight,  p.  366. 


b.   Blighted  field  which  less  than  week  before  photographed  was  perfectly  green,  p.  369. 
BLIGHT  OF    POTATO,   Phytophthora  infcstans. 


PLATE  XXXIII. 


b.   Section  through  blighted  tuber,  p.  364. 


a.   Late  stage  of  bliglited  leaves,  p.  366. 


c.   Blighted  tuber,  pitted  and  discolored  reddish  brown. 
BLIGHT   OF    POTATO,   Phylophthora  infcstans. 


PLATE  XXXIV. 


a.    Best  method  for  spraying  potatoes,  because  the  work  can  be  done  thoroughl}^  p.  373. 


b.   Less  satisfactory,    laecause  of   stationary  nozzles ;    pump,    also,    was   not    powerful 
enough  to  use  the  eight  nozzles,  p.  373. 

SPRAYING   FOR   POTATO  BLIGHT. 


PLATE  XXXV 


(X 


PLATE  XXXVI. 


a.   Spra3'ed  plant  in  Ogden's  field  ;  photographed  Sept.  i6,  igo2,  p.  370. 


b.   Check  or  unsprayed  plant  in  Ogden's  field  ;  photographed  same  dale,  p.  370. 
SPRAYING   FOR   POTATO  BLIGHT,  Pliylophlliora  iii/rslaits. 


PLATE  XXXVII. 


CJ 

CT- 

T3 

M 

o 

'o 

Ul 

0  (o 


State  of  Connecticut 


REPORT 


OF 


The  Connecticut  Agricultural 
Experiment  Station 

FOR  THE  YEAR  1905 

PART  V 
REPORT  OF  THE  STATION  BOTilNIST 


CONNECTICUT 

AaRICULTURAL    EXPERIMENT 
STATION 


REPORT  OF  THE   BOTANIST 

G,  P.  CLINTON,  Sc.  D, 


I.  Notes  on  Fungous  Diseases,  etc.,  for  1905. 

II.  Downy  Mildew,  Phytophthora  Phaseoli   Thaxt.,  of  Lima  Beans. 

III.  Downy  Mildew,  or  Blight,  Phytophthora  infestans  (Mont.)  DeBy.,  of 

Potatoes.     II. 


ISSUED  MAY,  1906 


NOTES    ON    FUNGOUS   DISEASES    FOR    I905.  263 

REPORT  OF  THE  BOTANIST. 


NOTES   ON   FUNGOUS   DISEASES,  ETC.,  FOR  1905. 

Fungous  diseases  during  the  year  1905,  on  the  whole,  were 
less  troublesome  to  cultivated  plants  in  Connecticut  than  for 
several  years  past.  This  was  due  to  the  comparatively  dry 
growing  season  up  to  the  first  part  of  August.  From  this  time 
on,  however,  the  weather  was  sufficiently  moist  to  develop  a 
few  troublesome  diseases,  belonging  chiefly  to  the  downy 
mildew  group.     The  more  important  of  these  were  as  follows : 

Brown  rot  of  peach,  Sclerotinia  fructigena,  probably  took  off 
a  third  of  the  crop  and  was  much  worse  than  usual,  being  one 
of  the  most  serious  fungous  outbreaks  of  the  year.  The 
injury  was  induced  by  the  rainy  weather  coming  on  just  about 
harvest  time.  The  loss  from  rot  was  felt  most  seriously  in  the 
Wallingford  district.  Plums,  also,  were  injured  but  less 
noticeably. 

The  downy  mildew  of  grapes,  Plasmopara  viticola,  was 
more  abundant  than  usual  this  year  but  no  especial  complaints 
were  received  concerning  it. 

Muskmelons,  though  not  now  so  generally  planted  because 
of  injury  from  fungous  enemies,  were  largely  a  failure, 
partly  because  of  the  attacks  of  the  leaf  mold,  Alternaria  Bras- 
sicae  var.  nigrescens,  and  of  the  downy  mildew,  Peronoplas- 
mopara  Cubensis.  The  latter  fungus  was  also  injurious  to  the 
cucumber,  though  the  injury  was  not  so  great  as  in  1901  and 
1902. 

The  downy  mildew  of  lima  beans,  Phytophthora  Phaseoli, 
was  more  destructive  than  it  has  been  since  1897.  The  oos- 
pores of  the  fungus  were  found  for  the  first  time,  though  the 
writer  and  others  had  previously  looked  for  them  very  care- 
fully. The  fungus  is  discussed  in  detail  in  a  special  article 
later  in  this  report.  The  rust  of  string  beans,  Uromyces 
appendiculatus,  also  seemed  to  be  more  prevalent  than  usual. 

The  downy  mildew,  or  blight,  of  potatoes  did  not  appear 
until  after  the  middle  of  August.  By  that  time  the  combined 
injuries  of  potato  bugs,  flea  beetles,  dry  weather,  and  early 


264        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O5. 

blight  (this  last  being  more  prominent  than  usual)  had  killed 
the  potatoes  in  many  fields,  so  that  these,  missing  the  blight  on  the 
foliage,  did  not  suffer  subsequently  from  rot  of  the  tubers. 
Those  fields,  however,  that  were  still  green  when  the  blight  did 
appear  were  gradually  killed  by  it  and  the  tubers  often  rotted 
considerably.  Thus,  while  there  was  considerable  com- 
plaint of  rotten  potatoes,  this  injury  was  not  as  great  as  in 

1904,  and  the  blight  injury  to  the  foliage  was  still  less 
conspicuous. 

Point-rot  of  tomato  did  some  damage  to  the  fruit — more 
than  has  been  noticed  for  several  seasons.  It  was  not  deter- 
mined whether  this  trouble  was  due  to  bacteria  or  fungi, 
but  superficial  observations  seemed  to  indicate  both  as  pri- 
mary agents  of  the  disease. 

New  Diseases. 

The  following  troubles  were  not  necessarily  especially 
injurious  in  1905  but  are  briefly  described  here  because  they 
have  not  been  mentioned  before  (see  Reports  of  Botanist  for 
years  1903  and  1904)  as  occurring  in  Connecticut. 

APPLE,  Pirus  Malus. 

Fruit  Speck_,  Fungus  undet.     Plate  XIII,  a.     In  February, 

1905,  Mr.  E.  M.  Ives  of  Meriden  gave  to  the  writer  for  exami- 
nation specimens  of  apples  showing  superficial  small  spots  or 
specks  scattered  over  the  skin.  This  trouble,  while  observed 
by  Mr.  Ives  at  harvest  time,  did  not  develop  conspicuously 
until  some  time  after  storage.  The  same  trouble  has  been 
observed  by  the  writer  the  present  winter  on  apples  in  the 
New  Haven  markets  and  also  on  specimens  of  the  Tallman 
variety  at  the  mid-winter  exhibition  of  the  Connecticut  Pomo- 
logical  Society.  These  areas  of  brownish  dead  tissue  usually 
varied  from  the  size  of  a  pin  head  to  a  quarter  of  an  inch  in 
diameter  and  extended  but  slightly  into  the  flesh.  The  dis- 
eased spots  in  some  cases  were  even  more  thickly  placed  than 
on  the  Tallman  Sweet  in  the  illustration  given  here.  Frequently 
one  could  see  at  the  center  of  the  specks  small  ruptures,  as  if 
made  by  insect-puncture,  or  possibly  the  trouble  started  at  the 
lenticels  and  these  were  of  that  nature.  Cultures  in  test  tubes 
were  made  at  different  times  by  taking  diseased  tissue  beneath 


NOTES    ON    FUNGOUS   DISEASES    FOR    I905.  265 

the  epidermis  with  a  sterilized  knife  and  these  all  developed  a 
fungous  growth  but  in  some  cases  mixed  with  bacteria.  As 
the  fungus  was  apparently  the  same  in  all  the  cultures,  pre- 
sumably it  was  the  primary  cause  of  the  trouble,  but  it  cannot 
be  a  very  aggressive  parasite  since  the  spots  remained  so  small 
and  developed  so  slowly  even  on  the  stored  fruit.  Neverthe- 
less it  is  a  serious  pest  for  certain  varieties  in  that  it  greatly 
mars  their  appearance  and  possibly  later  opens  the  way  for 
more  extended  and  deep-seated  rotting.  According  to  Mr. 
Ives,  Tallman  Sweet  was  the  variety  most  seriously  affected, 
Northern  Spy  suffered  less,  while  Baldwin  was  injured  but 
little.  From  this  it  would  appear  that  the  more  tender  or 
earlier  maturing  winter  varieties  were  more  susceptible  of 
attack.  Mr.  Ives  also  informs  the  writer  that  these  apple  trees 
were  sprayed  in  1905  and  the  disease  did  not  trouble  the  crop 
of  that  year.  No  reference  in  literature  has  been  seen  that 
relates  to  this  trouble,  which  apparently  is  a  common  one. 

BEAN,  LIMA,  Phaseohts  hmatus. 

Pod  and  Leaf  Blight,,  Phoma  subcircinata  E  &  E.  Plate 
XIII,  b.  Halsted  in  1892  briefly  mentioned  in  the  12th  Ann. 
Rep.  of  N.  J.  Agr.  Exp.  Stat.,  p.  287,  under  the  name  of  Phyl- 
losticta  sp.,  a  fungus  collected  on  the  pods  and  leaves  of  Lima 
beans.  In  1893  Ellis  also  described,  in  the  Proc.  Phil.  Acad. 
Nat.  Sci.,  a  new  fungus  on  the  pods  of  Lima  beans,  calling  it 
Phoma  subcircinata  E.  &  E.  In  a  more  detailed  description 
in  Bull.  151  of  the  N.  J.  Agr.  Exp.  Stat.,  p.  24-5,  Halsted 
identifies  Ellis'  fungus  as  the  one  to  which  he  had  previously 
referred.  The  past  year  the  writer  found  a  fungus,  apparently 
the  same  as  described  and  illustrated  by  Halsted,  on  the 
leaves  of  Lima  beans  in  the  vicinity  of  New  Haven.  It  was 
not  observed  on  the  pods  but  may  have  escaped  notice  because 
it  was  not  especially  looked  for  there.  While  attacking  leaves 
here  and  there  on  the  plants,  the  injury  was  not  especially  con- 
spicuous in  the  field.  The  fungus  produced  large  subcircular, 
or  more  irregular,  brown,  often  bordered,  spots  that  gave 
evidence  of  their  development  through  faint,  elevated,  con- 
centric rings  of  growth.  The  spore  receptacles  showed  as 
numerous  small  black  specks  immersed  in  the  tissues.  In  time 
the  dead  tissues  cracked  more  or  less  and  wore  away,  leaving 
17* 


266       CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

holes  in  the  leaves.  Our  specimens  do  not  agree  exactly  with 
those  issued  by  Ellis  (N.  A.  F.  No.  2840)  on  the  pods,  since 
their  spores  average  larger,  5-12/^  by  2.5-3.5/x,  and  are  occa- 
sionally septate.  This  might  be  considered  by  some  sufficient 
to  place  the  fungus  under  the  genus  Ascochyta,  and  Saccardo 
has  described  a  species,  A.  Phase olorum,  with  spores  10  by 
3ju,,  that  possibly  may  be  the  same  as  this. 

BUTTERNUT,  Juglans  cinerea. 

White  Mold,  Microstroma  Juglandis  (Berang.)  Sacc. 
This  is  not  an  uncommon  parasite  of  butternut  leaves,  forming 
white  moldy  growths  more  or  less  thickly  on  their  under  sides. 
Presumably  it  is  not  a  serious  pest.  Dr.  Britton  collected  speci- 
mens on  wild  butternuts  the  past  summer  at  New  Canaan. 

CATALPA,  JAPANESE,  Catalpa  Kempferi. 

Leaf  Spot,  Macrosporium  Catalpae  E.  &  M.  Plate  XIV,  a. 
This  trouble  was  conspicuous  during  the  past  summer  on  a 
Japanese  catalpa  at  the  Experiment  Station.  Reddish  brown, 
bordered  spots,  5  to  10  mm,  in  diameter,  are  formed  more  or 
less  abundantly  on  the  leaves.  The  tissues  of  these  spots  are 
dead  and  often  crack  apart,  sometimes  falling  out.  When  the 
trouble  is  serious  the  trees  are  partially  defoliated.  It  has  been 
observed  on  different  species  of  catalpa  in  various  parts  of  the 
United  States  and  has  been  discussed  most  extendedly  in  the 
Ann.  Rep.  U.  S.  Dept.  Agr.  for  1887,  pp.  364-5.  Experiments 
are  reported  there  in  which  spores  of  this  fungus,  and  also  of 
another  -found  with  it,  failed  to  produce  these  spots  when  sown 
on  catalpa  leaves.  From  what  the  writer  saw  of  the  disease 
he  has  been  led  to  believe  that  possibly  the  Macrosporium 
(Alternaria)  develops  on  the  leaves  as  a  consequence  and  not 
as  the  cause  of  these  dead  spots.  The  fungus  belongs  to  a 
genus  whose  species  are  more  often  saprophytic  than  para- 
sitic and  are  apt  to  occur  on  dead  tissues.  .  The  spores  were 
found  only  sparingly  on  the  dead  spots  and  sometimes  did  not 
seem  to  be  present.  No  other  fungus,  however,  was  observed 
on  these,  and  so  if  they  were  not  caused  by  the  Macrosporium 
they  probably  were  not  the  result  of  injury  by  any  other  fun- 
gus. Further  study  of  the  trouble  is  needed  to  definitely 
determine  its  cause. 


NOTES   ON    FUNGOUS   DISEASES    FOR    I905.  267 

GELEEIAC,    Apium  graveolens  var.  rapaceum. 

Leaf  Spot^  Septoria  Petroselini  var.  Apii  Br.  &  Cav. 
Plate  XIV,  b.  Celeriac  is  merely  a  variety  of  celery  having  a 
swollen  base.  It  is  not  largely  grown  in  Connecticut,  but 
specimens  raised  for  the  New  Haven  market  were  found  to  be 
injured  by  the  leaf  trouble  which  so  frequently  occurs  here  on 
celery  (see  Report  of  this  Station  for  1903,  p.  314). 

DANDELION",    Taraxacum  officinale. 

RusT^  Puccinia  Taraxaci  Plow.  This  rust,  so  common  on 
dandelions  as  weeds,  was  also  observed  on  dandelions  cultivated 
by  a  Highwood  market  gardener ;  but  it  was  not  causing  serious 
injury.  The  spores  form  dusty  reddish  brown  outbreaks,  about 
the  size  of  a  small  pin-head,  scattered  more  or  less  thickly  over 
either  surface  of  the  leaves. 

MAPLE,    SUGAR,    Acer  saccharum. 

Leaf  Scorch.  Plate  XV,  a.  During  the  past  summ.er  and 
fall  maple  leaves  similar  in  appearance  to  that  shown  in  the 
illustration  were  sent  to  the  Experiment  Station  from  different 
parts  of  the  state  with  inquiry  as  to  the  cause  of  the  trouble. 
Similar  specimens  and  requests  have  been  received  in  years 
past.  The  leaves  die  at  the  margins,  forming  irregular  brown 
patches  extending  inward  a  greater  or  less  distance.  Sometimes 
isolated  spots  are  formed  wholly  surrounded  by  healthy  tissue. 
In  time  there  often  appears  a  more  or  less  conspicuous  black- 
ish growth  of  saprophytic  fungi  on  the  dead  tissues.  The 
appearance  of  affected  leaves  moreover  is  very  similar  to  that 
produced  by  a  true  fungous  parasite  of  the  maple,  namely 
Glceosporium  saccharinum.  In  no  case,  however,  was  this  fun- 
gus found  on  the  leaves  sent  in  for  examination.  The  trouble 
is  undoubtedly  a  physiological  one,  such  .as  has  been  described 
by  Stone  of  Massachusetts  and  Stewart  of  New  York  as  occur- 
ring in  those  states.  For  some  reason  (due  probably  to  drought 
or  winter  injury  to  the  roots)  the  leaves  under  certain  weather 
conditions  are  not  able  to  replace  the  water  in  their  tissues  from 
the  roots  as  rapidly  as  it  is  lost  through  transpiration,  and  the 
death  of  the  tissues  from  the  margin  inward  results.  Accord- 
ing to  Stone  the  trouble  may  be  produced  by  unusually  favorable 


268        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I905. 

conditions  for  the  transpiration  of  water,  such  as  high  winds  on 
clear  warm  days,  when  the  available  water  supply  of  the  roots 
is  small.  Most  observers  report  the  trouble  as  appearing  sud- 
denly, A  somewhat  similar  injury  to  elm  leaves,  apparently  due 
to  the  same  causes,  has  also  been  reported  frequently  in  the 
state. 

NECTARINE,    Prunus  Persica  var,  necturina. 

Brown  Rot^  Sclerotinia  fructigena  (Pers.)  Schrot.  The 
nectarine  is  only  occasionally  grown  in  the  state,  but  these  few 
trees  seem  to  suffer  considerably  from  fungous  attacks  as  well 
as  from  winter  injury.  Specimens  of  the  mummied  fruit  col- 
lected in  January  showed  abundance  of  the  Monilia  stage  of  the 
brown  rot  fungous.  While  this  is  very  common  on  other  species 
of  Prunus  in  the  state,  it  has  not  been  reported  before  for  this 
host  though  apparently  not  uncommon  on  it. 

Scab,  Cladosporium  carpophilum  Thm.  Plate  XV,  b.  In 
September  specimens  of  nectarines  were  received  from  Thomp- 
son, Conn.,  that  were  badly  injured  by  the  scab  fungus  which 
is  so  common  in  Connecticut  on  the  peach.  As  the  nectarine  is 
a  smooth  fruit,  the  injury  more  nearly  resembles  that  produced 
by  scab  on  plums  than  that  on  the  peach.  The  skin  becomes 
more  or  less  thickly  covered  with  the  circular,  brownish  scab 
colonies  which  occasionally  merge  together.  The  fungus  incites 
the  formation  of  a  corky  growth  of  tissues  and  causes  more  or 
less  cracking  in  these.  The  badly  infected  fruit  is  said  to  drop 
prematurely  or  else  mature  imperfectly.  As  in  the  plum,  the 
injury  to  the  tissues  is  more  conspicuous  than  the  fungus,  while 
on  the  peach  it  is  the  olive  fungous  growth  that  forms  the  con- 
spicuous spots,  the  hairy  covering  no  doubt  protecting  the  fruit 
somewhat  and  at  the  same  time  permitting  a  more  vigorous 
external  growth  of  the  parasite.  An  examination  of  the  twigs 
seemed  to  indicate  that  the  fungus  carried  over  the  winter  on 
these  as  it  does  on  the  peach.  The  preventive  measures  are  the 
same  as  those  for  peach  scab  (see  Report  1903,  p.  340)- 

OKRA,  Hibiscus  esculentus. 

Wilt,  Neocosmospora  vasinfecta  (Atk.)  Sm.  Plate  XVI, 
a-b.  This  fungus  is  very  injurious  to  cotton  in  the  south  and 
was  first  described  by  Atkinson  (Bull.  Ala.  Agr.  Exp.  Stat.,  41 : 


NOTES    ON    FUNGOUS    DISEASES    FOR    IQOS-  269 

19-24)  in  1892.  He  mentions  in  this  bulletin,  p.  25,  that  okra, 
which  is  botanically  related  to  cotton,  is  sometimes  attacked. 
Smith  (Bull.  U.  S.  Dep.  Agr.,  Div.  Path.,  17:  31)  and 
Orton  {Ibid,  Bull.  2y :  6)  both  mention  okra  as  having  a  wilt 
disease  which  they  consider  the  same  as  that  of  cotton  though 
their  identity  has  not  been  absolutely  proved.  Okra  is  a  salad 
plant  occasionally  grown  in  private  gardens  in  this  state.  Some 
plants  in  the  Experiment  Station  grounds  the  past  year  showed 
unmistakable  signs  of  the  disease  in  August  and  September. 
The  year  before  some  cotton  had  been  grown  in  the  garden  a 
short  distance  from  where  the  okra  was  situated.  If  the 
disease  occurred  on  this,  however,  it  escaped  notice.  There  are 
a  number  of  these  wilt  troubles  of  cultivated  plants  that  have 
been  described  as  distinct,  such  as  wilts  of  cotton,  cucurbits, 
potato,  tomato,  flax,  etc.  Several  of  these  occur  in  this  state 
and  the  tomato  trouble  has  been  especially  bad  in  the  Experiment 
Station  greenhouse  for  years.  As  they  are  all  caused  by  Fusa- 
rium  soil  fungi  (of  which  the  mature  stage  has  been  observed 
only  in  one  or  two  cases)  and  these  act  much  the  same  on  all 
of  the  hosts,  there  may  be  some  question  whether  they  are 
really  caused  by  different  species  or  merely  strains  of  the  same 
semi-parasitic  soil  fungus. 

The  diseased  okra  plants  when  first  seen  by  the  writer  in 
September  looked  as  if  they  had  been  partially  killed  by  the 
frost ;  see  Plate  XVI,  a.  The  trouble  showed  first  on  the  lower 
leaves,  gradually  affecting  those  above  in  succession.  They 
became  yellowish  in  irregular  streaks  from  the  margin  inward 
and  eventually  brown  and  dead.  In  time  the  whole  leaf  is  killed 
and  it  is  usually  dehisced  at  the  customary  place  on  the  node ; 
see  Plate  XVI,  a.  Thus  a  badly  diseased  plant  may  gradually 
drop  all  of  its  mature  leaves  and  finally  begin  to  die  at  the  tip 
of  the  stem.  The  character  of  the  disease  is  shown  on  cutting 
transverse  or  longitudinal  sections  of  the  stem.  The  woody 
layer. which  occupies  a  prominent  band  between  the  central  pith 
and  the  outside  bark  appears  in  these  cases  plainly  diseased, 
having  a  dark  brown  color ;  see  Plate  XVI,  b.  This  discolora- 
tion of  the  wood  even  shows  when  the  outside  of  the  stem 
appears  normally  green  and  healthy.  Microscopic  sections 
demonstrate  that  the  diseased  condition  is  caused  by  the  pres- 
ence  of    the   Fusarium    stage    of    the    fungus    which    develops 


270        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

vigorously  in  the  vascular  bundles,  more  or  less  completely  fill- 
ing the  water-carrying  ducts  and  causing  disease  of  their  walls 
and  the  surrounding  tissues.  The  fungus  even  penetrates 
eventually  into  the  bundles  of  the  leaf  petioles.  Thus  the  water 
supply  of  the  leaf  is  gradually  cut  off  and  the  blade  finally  dies. 
These  wilt  fungi  apparently  develop  to  a  certain  extent  on 
decaying  rubbish  in  the  ground  and  thus  become  more  trouble- 
some from  year  to  year  if  the  land  is  used  consecutively  or  con- 
tinuously for  plants  liable  to  infection.  In  some  cases,  as 
unquestionably  with  the  tomato  wilt,  the  seeds  from  diseased 
plants  may  carry  the  trouble  and  serve  as  a  means  of  infection. 
The  continued  use  of  the  same  soil  in  hot  beds  favors  the 
establishment  of  the  fungus  there,  when  it  becomes  a  means  of 
infecting  the  young  plants  of  tomatoes  and  egg  plants.  Egg 
plants,  especially  when  transplanted  to  apparently  uninfected 
fields,  often  suffer  seriously,  even  though  they  showed  no  sign 
of  the  disease  in  the  young  plants  transferred  from  the  hot-bed. 
All  these  points  must  be  taken  into  consideration  in  combatting 
wilt  troubles.  Spraying,  because  of  the  infection  of  the  plants 
through  the  underground  parts,  is  of  little  use.  Apparently 
soil  treatment  with  chemicals  will  usually  be  of  little  practical 
value  though  based  on  good  theoretical  grounds.  Orton  was 
successful,  with  cotton,  in  rearing  plants  that  were  wilt  proof 
through  selection  of  wilt  resistant  individuals  in  the  infected 
fields. 

ONION,    Allium  Cepa. 

Brittle,  Fusarium?  Plate  XVII,  a.  Early  in  June,  1905, 
the  writer,  with  Dr.  Britton,  examined  an  onion  field  owned  by 
Mr.  Burton  W.  Bishop  of  Guilford  to  determine  the  cause  of 
a  disease  which  is  a  serious  menace  to  the  onion  industry  in 
that  region.  According  to  Mr.  Bishop,  at  least  one  hundred 
acres  of  desirable  onion  land  in  the  vicinity  of  Guilford  are  not 
available  for  growing  onions  because  of  this  trouble.  It  usually 
starts  in  some  section  of  a  field  and  spreads  in  area  from  year 
to  year,  as  the  onions  are  generally  grown  continuously  on  the 
same  land.  In  Mr.  Bishop's  field  the  disease  had  appeared  the 
year  before  near  a  stone  fence  and  this  year  was  occupying  a 
considerably  larger  area.  In  a  neighbor's  field  the  trouble 
apparently  started   from  a  spot  on  which  a  manure  pile  had 


NOTES    ON    FUNGOUS    DISEASES    FOR    I905.  2/1 

recently  stood.  A  report  from  Mr.  Bishop  after  the  onion 
season  was  over  showed  that  the  disease  did  not  progress  much 
later  in  the  season,  thus  indicating  that  it  is  chiefly  injurious 
to  the  young  plants.  At  the  time  of  the  visit  the  onions  in  the 
main  part  of  the  field  examined  were  several  inches  high  and 
well  beyond  the  dampening  off  stage.  In  the  infected  areas 
they  averaged  much  smaller  and  the  stand  was  very  poor.  Mr, 
Bishop  stated  that  the  weeds  in  these  infected  areas  usually 
made  a  poor  growth,  but  this  was  not  evident,  at  this  time,  to 
the  writer. 

One  of  the  most  general  characteristics  of  the  disease  is  the 
brittleness  of  the  onion  leaves,  from  which  character  the  disease 
takes  its  name.  Another  very  evident  character  is  the  peculiar 
curling  of  the  leaves  of  some  of  the  plants.  In  exaggerated 
cases  these  leaves  had  developed  spiral  coils  of  two  to  three 
turns,  as  is  shown  in  the  illustration.  Frequently  the  leaves 
are  unevenly  thickened  or  constricted  and  show  somewhat 
indefinite  yellowish  spots.  The  general  appearance  of  the  plants 
suggested  that  possibly  the  disease  resulted  from  insect  injury 
of  some  kind,  but  neither  Dr.  Britton  nor  the  writer  could  find 
any  evidence  to  support  this  theory.  Neither  was  there  any 
evidence  of  a  fungus  attack  on  the  parts  above  ground. 
Usually  the  roots  appeared  normal  when  the  plants  were  pulled 
up  and  later  examination  in  the  laboratory  showed  no  sign  of 
any  external  fungus  at  work  on  them.  However,  when  the 
plants  were  taken  very  carefully  from  the  ground  without  break- 
ing off  the  smaller  roots,  examples  were  found  in  which  some 
of  the  roots,  especially  toward  the  extremities,  showed  slight 
irregular  swellings,  and  these  roots  were  more  brittle  than  nor- 
mally but  otherwise  appeared  perfectly  healthy. 

Microscopical  sections  of  these  roots,  even  in  places  not  • 
enlarged,  showed  the  presence  of  an  internal  mycelium  of  some 
fungus.  The  m3^celial  threads  were  most  evident  in  the  inter- 
cellular spaces  around  the  parenchymatous  cells  and  not  infre- 
quently sent  conspicuous  irregular  branches  into  these,  causing 
plasmolysis  of  their  protoplasmic  contents,  but,  so  far  as 
observed  at  this  stage,  no  evident  injury  to  the  cell  walls. 
Apparently  the  presence  of  the  fungus  caused  an  unusual  local 
multiplication  of  the  parench3^ma  cells,  resulting  in  the  irregular 
swellings  of  the  roots.     No  sign  of  the  mycelium  was  found  in 


2/2        CONNECTICUT    EXPERIMENT   STATION    REPORT,    I905. 

the  tissues  above  ground  even  when  their  malformation  was 
conspicuous.  Probably  this  injury  resulted  in  some  way  from 
the  stimulating  or  irritating  action  of  the  mycelium  in  the  roots. 
Whether  later  in  the  season  the  fungus  penetrated  into  the  leaf 
tissues  or  caused  further  disease  of  the  roots  was  not  deter- 
mined. Specimens  of  the  infected  onions  left  exposed  for 
a  few  days  in  a  moist  chamber  developed  growths  of  several, 
apparently  saprophytic,  fungi,  but  no  special  growth  showed  on 
the  enlarged  roots.  The  most  conspicuous  of  these  external 
fungous  growths  was  that  of  a  species  of  Fusarium. 

Soil  from  an  infected  field  was  brought  to  the  Experiment 
Station  greenhouse  and  placed  in  two  boxes  and  a  third  box  was 
filled  with  the  soil  used  in  the  greenhouse.  Onion  seed  was 
planted  in  each  of  these,  but  in  one  of  the  boxes  of  Guilford 
soil  a  heavy  coating  of  a  mixture  of  lime  and  sulphur  was 
scattered  over  the  seed  in  the  rows  before  covering.  The  young 
plants  in  the  untreated  Guilford  soil  dampened  off  consider- 
ably more  than  in  either  of  the  other  two  boxes,  but  none  of  the 
plants  in  any  of  the  boxes  developed  the  peculiar  malformation 
or  brittleness  observed  on  the  diseased  onions  in  the  fields.  The 
plants  were  kept  under  observation  several  months.  Those 
grown  in  the  treated  soil  made  the  least  growth,  as  undoubtedly 
too  much  lime  and  sulphur  was  used  for  their  best  development ; 
those  in  the  untreated  Guilford  soil  had  a  poorer  stand  but 
made  a  slightly  better  growth ;  while  those  in  the  greenhouse 
soil  made  by  far  the  best  growth.  This  might  indicate  that  the 
Guilford  soil  was  somewhat  deficient  in  plant  food,  but  Mr. 
Bishop  states  that  it  had  been  liberally  fertilized. 

Everything  considered,  the  trouble  seems  to  be  caused  by 
some  soil  fungus,  possibly  a  Fusarium,  as  the  mycelium  observed 
•  in  the  roots  could  easily  belong  to  such  a  fungus  and  it  is 
known  that  this  genus  furnishes  several  soil  fungi.  Its  devel- 
opment in  the  onion  fields  seems  to  be  due  to  the  practice  of 
growing  onions  continuously  on  the  same  land  and  using 
manure  as  a  fertilizer.  Probably  the  disease  would  cease  to  be 
troublesome  if  a  proper  rotation  of  crops  on  the  land  was  fol- 
lowed, such  as  corn,  onions,  rye  and  clover,  using  stable  manure 
only  the  year  the  land  was  in  corn  and  commercial  fertilizers 
at  other  times,  especially  when  in  onions.  Possibly  when 
infected  land  is  used  the  trouble  could  be  lessened  by  isolating 


NOTES    ON    FUNGOUS    DISEASES    FOR    1905.  2/3 

the  infected  part  by  a  ditch  from  the  remainder  of  the  field  and 
by  the  use  of  chemicals,  such  as  sulphur  and  lime,  in  the  drills 
in  the  infected  area. 

PLTJM,    Prunus  sp. 

Bacterial  Black  Spot^  Pseudomonas  Pruni  Sm.  Plate 
XVII,  b.  In  the  summer  of  1904  Mr.  F.  L.  Perry  of  Bridge- 
port brought  to  the  Station  green  plums  showing  a  disease, 
apparently  of  bacterial  origin,  but  which  was  not  definitely 
determined  at  that  time.  The  past  summer  similarly  diseased 
plums  were  received  from  Rhode  Island,  and  at  our  request 
Mr.  Perry  sent  specimens  from  Bridgeport.  This  trouble, 
apparently,  occurs  only  on  the  Jananese  plums,  but  may  attack 
any  of  the  varieties  of  these,  according  to  growers.  The  green 
plums  show  conspicuous  black-purple  spots  which  are  often 
slightly  sunken.  These  spots  vary  in  size  up  to  half  an  inch 
in  diameter.  There  are  not  many  on  a  single  plum  and  these 
are  usually  isolated.  The  diseased  tissue  does  not  extend  much 
below  the  skin,  so  the  injury  is  quite  superficial.  Usually  only 
a  few  plums  scattered  over  the  tree  show  the  trouble,  but  occur- 
ring on  the  green  fruit  one  is  apt  to  fear  that  later  it  will 
develop  into  a  very  serious  pest.  This  does  not  happen,  as 
the  trouble  becomes  less  conspicuous  and  vigorous  on  the 
ripening  fruit  and  fails  to  spread  further.  Specimens  of  the 
nearly  grown  but  green  fruit  when  placed  in  a  moist  chamber 
in  the  laboratory  did  not  show  any  further  progress  of  the 
disease  though  kept  for  some  time  under  observation.  Cul- 
tures made  from  diseased  tissue  from  the  interior  uniformly 
gave  growths  of  a  yellow  motile  organism,  thus  showing 
bacteria  to  be  the  cause. 

So  far  as  found  by  the  writer,  this  disease  has  been  described 
only  by  Erwin  F.  Smith  in  short  notes  (Science,  17:  456-7, 
1903,  Ibid.,  21:  502,  1905)  from  his  extended  studies  of  the 
disease,  which  he  found  on  Japanese  plums  in  Michigan.  Dr. 
Smith  states  that  the  disease  also  occurs  on  the  leaves  form- 
ing numerous  small  water-soaked  spots  which  finally  may  end 
in  shot  holes.  The  writer  has  not  had  the  opportunity  to 
examine  infected  trees  to  see  whether  the  disease  affected  the 
leaves  here,  but  the  correspondents  have  ■  not  complained  of 
injury  to  these.  In  the  Report  of  this  Station  for  1903,  page 
337,  the  writer  called  attention  to  a  bacterial  spot  of  peach 
18 


274       CONNECTICUT   EXPERIMENT    STATION    REPORT,    I905. 

leaves  about  which  nothing  at  that  time  had  been  written.  The 
general  appearance  of  these  leaves  seems  to  be  similar  to  that 
described  by  Smith  for  the  diseased  plum  leaves.  No  cultures 
were  attempted  from  the  peach  leaves,  so  it  is  impossible  to 
state  definitely  whether  their  disease  was  caused  by  the  same 
organism  as  the  plum  disease.  Smith  discovered  in  his  investi- 
gations with  the  plum  spot  that  the  bacteria  gained  entrance 
into  the  leaves  and  fruit  through  the  stomates  and  for  some  time 
confined  their  development  to  the  substomatic  cavities.  He 
also  found  that  the  disease  was  chiefly  of  meristematic  tissue, 
which  accounts  for  its  failure  to  progress  with  the  maturity 
of  the  leaves  and  fruit.  While  the  disease  in  its  present  con- 
dition is  not  very  serious,  one  can  not  assume  that  it  will 
remain  so  since  it  may  spread  to  other  varieties  and  become  more 
virulent.  Though  of  bacterial  origin,  it  is  quite  different  from 
the  bacterial  blight  that  has  been  found  occasionally  on  the 
plum  and  commonly  on  the  pear,  etc.,  in  this  state. 

RASPBERRY,  Ruhus  sp. 

Grey  Mold,  Botrytis  patula  Sacc.  &  Berl.  This  fungus  was 
collected  at  the  Frisbie  farm,  Southington,  in  July,  1902,  on 
the  fruiting  canes.  These  were  dying  prematurely,  apparently 
from  the  attack  of  some  fungus.  While  this  fungus  was  by 
far  the  most  conspicuous  one  found  in  the  stems,  it  may  not 
have  been  the  primary  cause  of  the  injury,  as  the  cane  wilt 
fungus,  Leptosphaeria  Coniothyrium,  was  also  present.  The 
Botrytis  formed  a  greyish  growth  which  broke  out  in  small  sori 
on  the  epidermis,  but  these  were  often  so  closely  placed  that 
they  formed  a  conspicuous  felt-like  mat,  resembling  considerably 
that  of  a  vigorous  downy  mildew.  The  spores  are  large  and 
look  more  like  those  of  the  Peronosporeae  than  they  do  those 
of  Botrytis.  The  fungus  is  certainly  not  a  typical  Botrytis  and 
possibly  does  not  belong  to  that  genus,  but  further  study  with 
fresh  material  would  be  necessary  to  determine  its  exact  rela- 
tionship, as  it  is  difficult  to  say  from  the  old  material  how  the 
spores  are  borne.  This  species  was  described  in  1885  by 
Saccardo  and  Berlese  from  specimens  sent  by  Ellis  from  New 
Jersey.  In  the  Syll.  Fung.  4,  p.  25,  the  host  is  given  as  SalLv  (  f) 
which  is  apparently  S.  mistake,*   as  specimens  collected  by  Ellis 


*In  the  host  index,  volume  13  of  the  Syll.  Fung.,  both  Salix  sp.  and 
Ruhus  strigosus  are  given  as  hosts. 


NOTES    ON    FUNGOUS   DISEASES    FOR    I905.  275 

at  Vineland,  N.  J.,  June  28,  1884,  and  which  the  writer  has 
examined,  through  the  kindness  of  Dr.  Underwood,  from  the 
N.  Y.  Bot.  Garci.,  are  labeled  "on  living  red  raspberry  canes." 
Apparently  the  fungus  has  been  very  rarely  collected. 

SPINACH,  Spinacia  oleracea. 

Leaf  Mold,  Heterosporium  variabile  Cke.  Plate  XVIII,  a. 
Halsted,  of  New  Jersey,  who  has  issued  a  bulletin  on  the  fungi 
which  attack  spinach,  does  not  give  this  fungus  in  his  list,  though 
he  does  mention  other  molds  that  appear  on  the  old  leaves.  It 
was  described  originally  by  Cooke,  of  England,  in  Grevillea,  5, 
p.  123,  in  1877,  and  the  host  was  given  as  "languishing  leaves 
of  Spinacia,"  The  specimens  collected  by  the  writer  were  on 
leaves  of  spinach  obtained  in  the  New  Haven  market  in  January. 
Usually  only  the  outer  two  or  three  leaves  of  each  head  were 
attacked  by  the  fungus.  These  leaveis  showed  subcircular  dead 
spots,  about  a  quarter  of  an  inch  or  less  in  diameter,  which 
were  more  or  less  densely  covered  above  and  also  usually  below 
with  a  conspicuous  olive-black  moldy  growth.  When  the  spots 
were  thickly  placed  the  intervening  tissue  was  a  sickly  yellowish 
color  and  the  leaf  worthless.  Even  when  the  spots  were  not 
so  abundant  the  market  value  of  the  spinach  was  lessened 
because  of  its  appearance.  The  fungus  may  or  may  not  be  a 
true  parasite,  as  the  writer  has  often  seen  spinach  leaves  in  the 
fields  with  spots  on  them  but  with  no  sign  of  fungous  growth. 
That  it  is  not  a  very  vigorous  parasite  was  shown  by  its  presence 
being  limited  largely  to  the  older  leaves.  A  species  of  Alter- 
naria  which  produces  a  general  appearance  very  similar  to  this 
fungus  has  also  been  observed  on  the  older  leaves  of  spinach 
in  the  market. 

SaUASH,  Cucurhita  Pepo. 

Downy  Mildew,  Peronoplasmopara  Cubensis  (B.  &  C.) 
Clint.  The  squash  is  a  host  not  before  reported  for  this  fungus 
in  Connecticut.  The  appearance  of  the  infected  leaves  was  so 
different  from  that'  of  the  usual  hosts  that  the  writer  did  not 
recognize  the  trouble  at  the  time  of  collecting  it  but  mistook  it 
for  a  bacterial  leaf  spot.     The  leaves  were  thickly  covered  with 


276       CONNECTICUT   EXPERIMENT    STATION    REPORT,    I905. 

small  angular  brown  spots  which  were  more  conspicuous  on  the 
upper  than  on  the  lower  side  and  much  smaller  than  those 
ordinarily  seen  on  the  musk  melons  and  cucumbers.  There  was 
no  evident  growth  of  the  fungus  and  the  microscopic  examina- 
tion revealed  the  presence  of  only  a  few  conidiophores.  The 
spores,  apparently,  averaged  smaller  than  on  some  of  the  other 
hosts. 

STRAWBEREY,  Fragaria  sp. 

Leaf  Scorch.  About  the  last  of  June,  1905,  Dr.  Britton  and 
the  writer  visited  Mansfield  Bros.'  farm  at  West  Hartford 
to  determine  the  cause  of  an  unusual  trouble  of  their  strawberry 
plants.  Many  of  these  were  drying  up  and  dying.  The  older 
plants  suffered  more  than  the  younger  and  the  older  leaves 
before  the  newer  leaves  on  the  same  plant.  The  leaves  turned 
purplish  and  then  gradually  dried  up  and  died.  No  sign  of 
insect  or  fungous  work  was  visible  on  them  and  an  examination 
of  the  roots  and  crowns  gave  no  indication  of  any  special  pest 
as  the  cause  of  the  injury.  The  plants  suft"ered  most  where 
the  matted  row  method  of  culture  was  used.  As  the  early  sum- 
mer had  been  unusually  dry,  the  writer  finally  came  to  the 
conclusion  that  this  was  largely  responsible  for  the  trouble, 
though  this  injury  did  not  show  prominently  until  the  very 
dry  weather  was  past.  Possibly  the  trouble  was  aggravated  by 
winter  injury  of  the  roots  and  the  method  of  culture,  which 
was  not  so  well  adapted  to  dry  weather. 

Powdery  Mildew^  Sphaerotheca  Humuli  (D.  C.)  Burr. 
Plate  XVIII,  b.  This  mildew  had  not  been  collected  in  the 
state  until  last  June,  when  Dr.  Britton  found,  at  Poquonock,  a 
few  infected  plants  in  a  field  near  a  manure  pile.  It  is  a  trouble, 
however,  that  is  rarely  reported  injurious  to  the  strawberries. 
The  leaves  become  covered  on  either  surface,  but  showing  most 
conspicuously  on  the  upper,  with  a  mealy  white  growth  of  the 
fungus.  This  is  the  conidial  or  summer  stage  and  the  winter 
spore  stage  is  rarely  formed  on  this  host. 

TOBACCO,  Nicotiana  Tahacum. 

Dampening  off,  f  Sclerotinia  sp.  Plate  XIX,  a-b.  Several 
seed-bed  troubles  of  tobacco  have  been  described  by  Selby  in  a 
recent  bulletin,  No.  156,  of  the  Ohio  Experiment  Station,  but 


NOTES    ON    FUNGOUS    DISEASES    FOR    I905.  2/7 

apparently  the  one  mentioned  here  is  different  from  any 
described  by  him.  In  appearance,  Plate  XIX,  b,  the  injured 
plants  were  very  similar  to  those  figured  by  Selby  for  a  bed-rot 
injury  caused  by  a  Rhizoctonia  fungus,  but  examination  o°f  the 
specimens  received  here  did  not  reveal  the  presence  of  this 
fungus.  The  disease  showed  on  the  young  plants  at  the  base 
of  the  stem  as  a  conspicuous  dead  area  or  a  complete  girdle. 
Often  the  injury  was  so  severe  as  to  cause  the  death  of  the  plant. 
When  placed  in  a  moist  chamber  the  infected  plants  produced 
a  growth  of  a  sterile  white  fungus  at  the  injured  part.  Plate 
XIX,  a,  shows  cultures  of  this  fungus  growing  on  potato  agar. 
These  cultures  never  produced  any  spores  but  instead  formed 
the  numerous  small  sclerotia  similar  to  some  of  those  described 
by  Smith  for  the  Sclerotinia  drop  fungus  of  lettuce,  which  is 
also  a  soil  fungus. 

Mr.  W.  E.  Frost  of  Bridgewater,  who  sent  the  diseased 
tobacco  plants,  wrote  in  part  as  follows :  *Ts  there  anything 
that  can  be  done  to  stop  the  rotting  of  tobacco  plants  in  the  seed 
beds?  Where  they  rotted  last  year  they  are  doing  so  this  year. 
Can  anything  be  done  so  that  it  will  not  appear  in  the  same  beds 
another  year?  Would  it  be  safe  to  set  plants  from  beds  where 
there  is  some  rot  if  the  plants  appear  all  right  when  taken  up  ?" 
Fungous  troubles  in  seed  beds  are  chiefly  due  to  two  conditions : 
first,  keeping  the  plants  too  moist  by  improper  watering,  insuf- 
ficient ventilation  or  crowding  the  plants  too  closely  together; 
second,  fertilizing  with  manure  or  using  the  same  soil  in  the 
beds  year  after  year,  thereby  establishing  in  these  special  injuri- 
ous soil, fungi.  When  the  trouble  is  of  the  second  sort,  as  in 
the  present  case,  the  soil  should  be  changed  or  new  beds  made 
and  where  feasible  only  artificial  fertilizers  should  be  used. 
Applications  of  lime  and  sulphur  to  infected  soil  possibly  in 
some  cases  may  prove  of  benefit.  In  answer  to  the  last  question 
asked  by  Mr.  Frost,  it  may  be  stated  that  the  writer  set  out 
some  of  the  least  diseased  plants  received  and  these  did  not 
develop  the  trouble  any  further  and  did  fairly  well  during  the 
whole  season.  There  are  some  diseases,  however,  contracted 
in  the  seed  beds,  as  the  wilt  of  egg  plants,  where  the  infected 
individuals  do  poorly  the  whole  season. 


2/8        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

DOWNY    MILDEW,    Phytophthora    Phaseoli    Thaxt.,    OF 
LIMA    BEANS. 

In  the  Botanical  Gazette  (18)  and  the  Annual  Report  of  this 
Station  (19)  for  1889,  Professor  Thaxter,  then  botanist  of  the 
Station,  recorded  the  discovery  of  the  Lima  bean  ^mildew,  which 
he  found  doing  damage  in  Connecticut.  Besides  giving  a 
general  and  scientific  description  of  the  fungus,  Thaxter 
described  and  illustrated  in  detail  the  parasitic,  or  summer  stage, 
but  he  was  not  successful  in  discovering  the  oospores,  or  winter 
stage.  His  successor.  Dr.  Sturgis,  also  in  the  Botanical 
Gazette  (16)  and  the  Reports  of  the  Station  (15,  17)  added  to 
our  knowledge  of  the  fungus  by  describing  its  methods  of 
infection,  especially  that  accomplished  by  the  aid  of  insects,  and 
recorded  successful  spraying  experiments.  He,  too,  failed  to 
find  the  oospores,  though  special  search  was  made  for  them. 
The  writer  adds,  in  this  paper,  his  contribution  to  the  knowledge 
of  the  fungus  in  a  description  of  the  missing  oospores  and  of 
artificial  cultural  experiments.  Practically  all  that  is  known 
of  the  mildew,  except  its  limited  distribution,  has  resulted  from 
the  work  of  the  botanists  of  this  Station.  It  is  fitting,  there- 
fore, that  a  detailed  account  of  the  fungus,  its  injury  and 
methods  of  prevention,  be  given  in  this  place. 

PARASITIC,  OR  SUMMER  STAGE. 

Relationships.  The  Lima  bean  mildew  belongs  to  the  small 
genus,  Phytophthora,  which  is  especially  characterized  among 
the  downy  mildews  by  the  nodular  swellings  on  the  conidio- 
phores  (spore-bearing  threads)  that  mark  the  position  of  the 
successively  developed  spores.  The  genus  includes  serious 
parasitic  pests,  the  most  conspicuous  of  which  is  the  downy 
mildew,  or  blight,  of  potato.  This  is  the  only  other  species 
that  occurs  in  Connecticut.  Another  species,  found  in  the  East 
Indies,  has  tobacco  for  its  host,  and  a  fourth  is  injurious  to 
seedlings  of  beech,  Coniferae,  etc.  One  or  two  other 
species  have  been  described  recently.  Apparently  the  mildew 
of  Lima  beans  is  most  closely  related  botanically  to  the  species 
that  occurs  on  tobacco. 

Distribution.  Thaxter  first  found  the  Lima  bean  mildew  in 
September  of  1889  at  Hamden,  Conn.,  near  New  Haven,  where 


DOWNY    MILDEW    OF   LIMA    BEANS.  279 

it  had  been  injurious  at  least  two  years  before  his  discovery. 
In  the  Report  for  1890  (20)  he  writes:  "This  mildew  (Phyto- 
phthora  Phaseoli)  described  and  figured  in  last  year's  report, 
has  been  again  destructive  this  year  and  has  made  its  appear- 
ance in  a  number  of  new  localities  in  the  neighborhood  of  New 
Haven.  So  far  as  ascertained  it  extends  from  New  Haven  to 
Hartford  and  west  to  South  Norwalk,  but  has  not  yet  been 
discovered  outside  of  Connecticut."  So  far  as  recorded,  Stur- 
gis'  work  and  observations  on  the  fungus  were  in  the  vicinity 
of  New  Haven  (East  Haven,  Westville,  etc.).  The  writer's 
experience,  too,  has  been  limited  to  this  vicinity,  though  com- 
plaint of  it  has  been  received  from  Green's  Farms.  Probably 
the  fungus  has  appeared  in  Connecticut  (in  a  more  or  less 
conspicuous  way)  each  year  since  its  discovery.  Thaxter  col- 
lected specimens  in  1889  and  1890.  Sturgis  records  it  as  being 
injurious  "for  some  years"  in  1893  but  failed  to  find  it  that 
year  in  localities  where  it  had  always  been  abundant;  he  also 
records  it  for  the  years  1897  and  1898  and  states  it  was  prevalent 
for  two  or  three  years  previous.  Rorer  collected  specimens  in 
1901  and  the  writer  made  collections  in  1902,  1903  and  1905. 

Outside  of  Connecticut  the  fungus  was  first  reported  in  New 
Jersey  by  Halsted  (4)  in  1897,  and  he  has  found  it  several 
times  since  in  the  same  state.  It  was  also  reported  about  this 
time  by  Speschnew  (13)  from  Tiflis,  Russia,  and  has  been  found 
by  other  Russian  botanists.  Smith  (12)  states  it  was  injurious 
in  1903  in  Delaware.  So  far  as  the  writer  has  learned,  these 
are  the  only  published  records  of  distribution.  Thinking  that 
possibly  it  had  been  noticed  but  not  reported  in  other  of  our 
eastern  states,  where  the  chances  for  its  introduction  and  devel- 
opment seemed  favorable,  information  on  this  point  was  asked 
of  the  Division  of  Vegetable  Pathology  and  Physiology  of  the 
U.  S.  Department  of  Agriculture  and  of  the  Experiment  Station 
botanists  of  fourteen  states,  chiefly  those  bordering  on  the  Atlan- 
tic coast.  Letters  received  from  these  showed  that  the  mildew 
had  not  been  observed  in  any  other  states  than  those  mentioned 
except  in  two  cases.  Mr.  Stewart,  of  the  Geneva  Station, 
N.  Y.,  reports  the  receipt  of  specimens  from  Long  Island  once 
each  in  1904  and  1905,  and  Mr.  Woods,  of  the  Division  of  Vege- 
table Pathology  and  Physiology  at  Washington,  states  that  the 
fungus  was  very  injurious  in  Frederick  county,  Maryland,  in 
1905. 


280       CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

Injury  to  host.  So  far  as  reported,  only  the  Lima  bean, 
Phase olus  lunatus,  is  subject  to  the  attacks  of  this  mildew.  The 
writer  has  seen  it  on  both  the  pole  and  dwarf  varieties,  though 
rarely  on  the  latter.  The  dwarf  varieties  are  not  usually  grown 
on  a  commercial  scale  in  Connecticut  and  probably  do  not  pre- 
sent so  favorable  conditions,  as  regards  moisture,  for  the  spread 
of  the  fungus,  though  Sturgis  has  reported  a  case  where  they 
were  severely  injured.  The  pods  are  the  parts  of  the  host  most 
subject  to  attack,  but  the  fungus  also  occurs  to  a  limited  extent 
on  the  young  leaves,  vines  and  flowers. 

The  growth  of  the  fungus  on  the  pods,  Plate  XXII,  a-b,  is 
often  very  conspicuous,  forming  a  dense  pure  white  felt  of  the 
conidiophores  in  irregular  patches,  or  sometimes  spreading  over 
the  entire  surface,  on  one  or  both  sides.  Both  Thaxter  and 
Sturgis  have  noted  that  the  mildew  often  at  first  is  present  only 
on  one  side  of  a  pod,  and  the  latter  states  that  this  is  usually 
the  side  furthest  from  the  vine  and  least  protected  by  the 
leaves.  The  injury  to  the  pod  generally  shows  but  little  beyond 
the  area  covered  by  the  fungus,  though  the  green  of  the  healthy 
tissue  may  be  separated  from  the  diseased  by  a  more  or  less 
distinct  purplish  border.  As  a  pod  becomes  more  and  more 
severely  injured  it  ^yilts  and  gradually  dies,  shriveling  up  in 
the  irregular  form  shown  in  the  illustration.  The  fungus  event- 
ually penetrates  into  the  interior  of  the  pod,  causing  the  tissues 
to  become  sunken,  and  the  mycelium  may  enter  the  seeds.  Many 
pods  are  attacked  so  vigorously  in  their  infancy  that  they  are 
killed  outright  and  others  are  injured  so  they  never  mature. 
The  injury  to  the  large  pods  varies  with  the  abundance  of  the 
fungus,  but  even  when  not  preventing  maturity  of  the  seeds  it 
may  still  affect  their  market  value  by  injuring  their  appearance. 
The  mildew  opens  the  way  for  further  injury  to  the  pods  and 
seeds  by  other  fungi,  so  that  quickly  following  its  prime  devel- 
opment there  appear  such  fungi  as  Fusarium,  Alternaria, 
Cladosporium,  etc.  The  growths  of  these  eventually  discolor 
the  pure  white  of  the  mildew. 

The  attack  of  the  fungus  on  the  flowers  is  not  usually  very 
conspicuous,  though  it  is  through  insect  visitation  to  these,  as 
shown  by  Sturgis,  that  the  infection  of  the  young  pods  often 
takes  place.  So,  too,  the  leaves,  petioles  and  vines  are  gen- 
erally   not    much    injured    and    apparently    are    infected    only 


DOWNY    MILDEW    OF   LIMA    BEANS.  28 1 

in  their  young  state.  The  infected  leaves  often  show  an 
irregular  injury  of  the  tissues  with  more  or  less  of  a  purplish 
discoloration,  especially  on  the  veins,  and  there  is  no  very  evident 
growth  of  the  fungus  showing  on  them.     See  Plate  XXI,  b. 

Financial  loss.  In  this  state  a  few  Lima  beans  are  usually 
grown  by  each  farmer  for  home  consumption  and  most  garden- 
ers grow  the  pole  varieties  in  quantities  for  the  market.  They 
are  probably  raised  most  extensively  around  New  Haven,  though 
each  large  city  has  more  or  less  grown  in  its  vicinity.  The 
largest  grower  in  the  state,  A.  N.  Farnham  of  Westville,  often 
plants  twelve  or  more  acres  and  sometimes  most  of  these  are 
in  a  single  large  field.  The  financial  loss  due  to  injury  by  the 
mildew  comes  chiefly  on  the  market  gardeners  and  is  greatest 
in  those  localities  where  the  beans  are  grown  extensively. 
Thaxter's  statement,  based  on  his  observations  at  Hamden,  that 
the  mildew  "bids  fair  to  become  the  most  serious  obstacle  yet 
encountered  in  the  cultivation  of  this  vegetable,"  especially  in 
the  Atlantic  seaboard  states,  was  not  exaggerated.  Sturgis 
wrote  that  "during  the  summer  of  1897  the  conditions  were 
such  that  in  many  places  the  effects  of  the  fungus  have  been 
most  disastrous."  In  1898,  in  a  number  of  counts  in  a  certain 
field,  he  found  that  the  percentage  of  pods  attacked  by  the  mil- 
dew varied  from  36  to  53  per  cent,  of  the  total  number  pro- 
duced during  the  season.  The  writer's  observations  on  the 
disease  began  in  1902,  when  the  fungus  did  considerable  dam- 
age, especially  in  the  lower,  more  moist  places  in  the  fields. 
During  the  next  two  years  there  was  comparatively  little  injury, 
but  in  1905  the  loss  caused  by  it  was  the  greatest  since  1897. 
In  one  of  the  largest  fields  in  the  state,  the  grower  estimated 
that  the  yield  was  cut  down  about  one-third  by  this  pest. 

Halsted  (4)  states  that  the  mildew  was  so  serious  in  New 
Jersey  in  1897  that  "few  or  no  pods  were  picked  from  some 
of  the  fields."  He  also  reports  numerous  complaints  of  it  in 
that  state  in  1902.  Smith  (12)  records  the  mildew  as  injuri- 
ous in  Delaware  in  1903 ;  and  Woods  in  a  letter  to  the  writer 
states  that,  in  Frederick  county,  Maryland,  in  1905,  "it  is  said 
to  have  destroyed  from  25  to  90  per  cent,  of  the  crop." 

Relation  to  zveather.  The  prevalence  of  most  parasitic  fungi 
is  largely  influenced  by  the  character  of  the  weather,  particu- 
larly  in  regard  to  moisture.     This   is   especially   true  of   the 


282        CONNECTICUT   EXPERIMENT   STATION    REPORT,    1905. 

downy  mildews.  An  abundance  of  rainy  or  cloudy  weather  at 
certain  periods  of  the  year  determine  whether  or  not  these 
troubles  will  be  injurious.  July,  August,  and  to  a  less  degree 
September,  are  the  months  in  which  unusual  moisture  develops 
the  downy  mildew  of  the  Lima  bean,  just  as  it  does  the  downy 
mildew,  or  blight,  of  the  potato.  So  far  as  yet  ascertained,  the 
middle  of  July  is  the  earliest  that  the  Lima  bean  mildew  has 
been  found  in  this  state  and  frequently  it  does  not  appear 
until  the  middle  of  August.  After  its  appearance  it  can  be 
found  more  or  less  abundant,  according  to  the  weather,  up  to 
the  time  the  vines  die.  Halsted  (6)  notes  the  fungus  as  late 
as  October  24  on  green  pods,  after  the  leaves  had  been  killed  by 
frost,  and  the  past  year  the  writer  collected  it  in  several  fields 
on  October  4  under  the  same  conditions.  Sturgis  reports,  how- 
ever, that  in  1897  "for  some  reason  not  wholly  clear,  perhaps 
because  of  lessened  insect  activity,  the  mildew  ceased  spreading 
about  September  loth." 

From  the  published  data  it  seems  quite  certain  that  trouble 
from  the  mildew  may  generally  be  expected  in  very  moist  years. 
Halsted  (5),  writing  on  this  point,  says:  "The  year  1897  had 
its  counterpart  in  that  of  1889.  During  the  past  ten  years  there 
have  been  in  the  Eastern  States  two  Julys  noted  for  their 
excess  of  rainfall  (1889  and  1897).  ...  In  connection 
with  what  has  been  said  above  concerning  the  influence  of 
copious  rainfall  upon  the  unusual  development  of  the  potato 
rot,  it  is  in  order  to  report  that  another  member  of  the  genus 
Phytophthora  [the  Lima  bean  mildew]  has  been  complained  of 
bitterly  during  the  season  of  1897.  .  .  Particular  empha- 
sis is  placed  upon  the  date  of  the  discovery  [1889]  ^^*^  the  fact 
that  it  was  very  abundant  at  the  time  it  was  taken,  because 
that  was  the  year  in  which  the  three  months  of  July,  August 
and  September  gave  a  total  rainfall  of  27.33  inches  for  New 
Jersey  and  presumably  as  wet  in  Connecticut;  which  is  9.54 
inches  more  than  the  average  of  those  three  months  for  the 
past  ten  years."  Besides  in  1889  and  1897,  the  mildew  was 
unusually  abundant  in  1902,  which  year  was  characterized  by 
cold  damp  weather  in  July  and  August,  and  again  in  1905,  which 
though  dry  previous  to  the  middle  of  August  was  rather 
moist  the  remainder  of  the  month  and  during  the  first  part  of 
September, 


DOWNY   MILDEW    OF   LIMA   BEANS.  283 

The  middle  Atlantic  seaboard  states  apparently  offer  the 
best  conditions  for  the  development  of  the  fungus,  and  as  it  has 
spread  into  most  of  these,  there  may  be  expected  increasing 
trouble  from  the  pest  in  their  market  garden  districts  in  years 
with  very  moist  weather  during  July  or  August.  Not  many 
Lima  beans  are  grown  in  New  England  north  of  Connecticut. 
In  the  drier  middle  and  western  states  less  injury  may  be 
expected  should  the  fungus  become  introduced,  except  possibly 
in  localities  affected,  as  to  moisture,  by  the  Great  Lakes. 

Methods  of  distrihution.  The  means  by  which  the  fungus 
spreads  over  the  vines  after  it  once  gets  started  in  a  field  and 
presumably  by  which  it  is  carried  to  some  extent  from  one  field 
to  another,  have  been  discussed  somewhat  in  detail  by  Sturgis. 
He  found  that  both  insects  and  wind  were  important  agents 
in  its  distribution.  Rains  also  aid  greatly  by  washing  the 
spores  from  the  infected  parts  over  the  same  plant. 

Concerning  insects  as  agents  of  distribution,  we  quote  from . 
Sturgis   (15)   as  follows: 

"The  occurrence  of  the  mildew  on  the  pods  at  a  very  early  stage  of 
their  growth,  led  to  the  supposition  that  insects  were  responsible  in  a 
measure  for  the  spread  of  the  fungus.  Examination  of  the  flowers 
served  to  confirm  this  supposition,  and  a  few  words  regarding  the  struc- 
ture of  the  bean  flower  will  explain  how  infection  takes  place.  The 
conspicuous  portions  of  the  bean  flower  consist  of  an  upright  petal  known 
as  the  standard;  two  narrower  petals,  distinct,  projecting  forward  below 
the  standard  and  known  as  the  wings;  and  two  petals  in  the  form  of 
a  closed,  spirally  coiled  tube  occupying  a  position  between  the  standard 
and  the  wings,  and  called  the  keel.  (Fig.  8,^)  At  the  base  of  the 
keel  is  the  ovary  or  young  pod  surrounded  by  the  stamens  and  prolonged 
upwards  into  the  style.  The  long  stamens  and  style  are  completely 
enclosed  in  and  protected  by  the  keel.  Under  such  conditions  cross- 
fertilization  would  seem  to  be  impossible,  especially  as  the  pollen  is 
shed  abundantly  from  the  anthers  which  are  borne  upon  the  stamens  in 
close  proximity  to  the  upper  portion  of  the  style,  and  neither  the  stigma 
nor  the  anthers  appear  beyond  the  end  of  the  tube  in  which  they  are 
enclosed.  But  the  wings  form  a  convenient  resting  place  for  visiting 
bees  in  search  of  nectar,  and  in  case  a  bee  lights  upon  them  his  weight 
deflects  them  and  at  the  same  time  draws  the  keel  down  and  backward, 
thus  causing  the  stigma  and  the  hairy  portion  of  the  style  covered  with 
pollen  to  protrude  from  the  mouth  of  the  tube.  (Figs.  8,^'^)  As  the 
insect  plunges  his  head  into  the  flower,  the  stigma  and  pollen-laden 
style  come  into  contact  with  his  abdomen  and  cross-fertilization  is 
assured  by  subsequent  visits  to  other  flowers.     But  fungous  infection  is 


284       CONNECTICUT    EXPERIMENT   STATION   REPORT,    I905. 

assured  with  hardly  less  certainty,  provided  the  bee  has  previously  had 
contact  with  the  spores  of  the  fungus.  In  that  case  we  should  expect 
to  find  the  first  attack  of  the  fungus  at  the  two  points  where  the  bee, 
in  his  search  for  nectar,  touched  the  more  moist  and  delicate  tissues  of 
the  flower;  viz.  on  the  style  and  at  the  base  of  the  ovary  or  pod.  A 
large    number    of    flowers    was    examined    and    this    supposition    was 


t_V____d. 


A—f. 


Fig.  8.  Showing  details  of  bean  blossom  with  reference  to  infection  with 
mildew  by  bees.  i.  Parts  of  blossom:  a.  standard,  b.  keel,  c.  wings.  2. 
Showing  how  the  weight  of  a  bee  alighting  on  the  wings  causes  protrusion 
of  style,  d.  3.  An  enlarged  keel  in  cross-section,  showing  enclosed  pistil 
with  young  ovary  or  pod  at  its  base,  e.  4.  Pistil  showing  growths  of  mil- 
dew (f.)  at  base  and  apex  of  the  young  pod  resulting  from  spore  inoculation  by 
bee  visitation  during  blossoming  period.     (1-2  after  Gray;  3-4  after  Sturgis.) 


strikingly  confirmed.  The  mildew  was  found  in  many  of  the  flowers, 
and  in  every  case  it  occurred  on  the  spots  above  mentioned  and  nowhere 
else.  (Fig.  8,  *)  It  seems  certain,  therefore,  that  the  spread  of  this 
mildew  is  largely  due  to  the  agency  of  insects,  particularly  of  bees,  and 
this  view  is  further  confirmed  by  the  fact  that  in  the  case  of  young  pods 
the  mildew  almost  always  appears  first  at  the  base  or  tip  and  very  rarely 
in  the  middle." 


DOWNY    MILDEW    OF    LIMA   BEANS. 


285 


The  influence  of  wind  on  the  distribution  of  the  fungus  in 
a  field  is  shown  by  the  following  account,  also  quoted  from 
Sturgis : 

"The  Lima  beans  on  the 
Station  grounds  are  on  high 
land  composed  of  a  light 
sandy  soil,  and  have  never 
been  affected  with  mildew. 
The  rows  run  east  and  west. 
Directly  south  of  them  at  a 
distance  of  about  one  hun- 
dred feet,  but  separated  from 
them  by  a  pile  of  lumber  and 
a  few  trees,  are  two  rows  of 
bush  Limas  running  north 
and  south.  On  August  14th, 
when  the  mildew  had  been 
abundant  in  the  neighbor- 
hood for  a  month  or  more, 
the  Station  vines  were  exam- 
ined and  found  to  be  entirely 
free  from  the  fungus.  A 
few  mildewed  pods  were 
brought  from  a  distance,  and 
the  spores  from  one  of  them 
were  rubbed  and  dusted  on 
the  surface  of  a  sound  and 
nearly  ripe  pod  at  the  east 
end  of  each  row  of  the  pole 
Limas.  Within  a  few  days 
the  mildew  made  its  appear- 
ance on  the  infected  pods, 
and  from  this  point  of  van- 
tage, the  prevailing  winds  at 
the  time  being  from  the 
northeast  and  north,  it  swept 
down  both  rows  and  in  two 
weeks  the  whole  patch  was 
completely  mildewed.  The 
spores  had  also  been  carried 
over  a  distance  of  one  hun- 
dred feet  to  the  bush  Limas, 
and  the  mildew,  beginning 
at  the  north  end  of  the  rows, 
that  is,  at  the  point  nearest 

to    the     pole    beans,     spread  ^^^   ^      Details  of  conidial  stage, 

rapidly   down    the   rows.     It  (After  Thaxter.) 


286       CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

is  evident  then,  that  spores  placed  upon  the  surface  of  a  sound  Lima  bean 
pod  were  enabled  to  start  the  disease,  which  thereupon  spread  with 
great  rapidity  in  the  direction  of  the  prevailing  wind." 

Microscopic  structure.  Having  considered  the  more  general 
character  of  the  fungus  and  its  environmental  factors,  let  us 
proceed  to  a  study  of  its  minute  structure  as  revealed  by  the 
microscope.  For  a  preliminary  account  we  can  do  no  better 
than  to  give  Thaxter's  (19)  description: 

"Examination  of  a  section  of  the  diseased  tissue  shows  it  to  be 
penetrated  by  the  irregular  branching  hyphse  of  the  fungus  [mycelium] 
which  run  between  the  cells  and,  collecting  in  the  air  spaces  beneath 
the  breathing  pores,  push  out  through  them  into  the  air  (Fig.  9,^")  in 
such  numbers  that  the  latter  are  completely  obliterated.  These  hyphse 
(Fig.  9,'"),  just  at  their  point  of  exit  from  the  breathing  pores,  are 
usually  slightly  swollen  and  give  rise  to  one  or  more  branches  [conidi- 
ophores]  which  grow  almost  vertically  into  the  air,  and,  taken  together, 
produce  the  white  woolly  appearance  already  mentioned  as  characteristic 
of  the  disease.  These  vertical  branches  may  themselves  be  once  dicho- 
tomously  branched,  that  is  give  rise  to  two  branches,  forming  a  more 
or  less  symmetrical  fork;  while  at  their  tips  they  swell  out  into  the 
large,  terminal,  oval  conidial  spores  represented  in  the  figure.  A  pecu- 
liarity of  the  genus  Phytophthora  consists  in  the  fact  that  after  a  spore 
has  been  produced  at  the  apex  of  .a  hjnpha,  the  hypha  continues  to  grow 
at  the  point  where  the  spore  is  attached,  pushing  it  to  one  side  if  it 
has  not  already  fallen  off,  and  soon  swelling  into  another  spore.  This 
may  be  repeated  several  times,  the  points  where  spores  have  been  pre- 
viously formed  being  marked  by  successive  vesicular  swellings  (Fig. 
9,"^)." 

The  myceliiim  is  similar  to  that  usually  formed  by  the  dovvmy 
mildews.  Its  hyaline  threads,  Plate  XX,  1-6,  are  more  or  less 
branched,  are  occasionally  somewhat  irregular  in  shape  and 
have  a  comparatively  thin  cell  wall  which  on  staining  with  chlo- 
roiodide  of  zinc  shows  the  presence  of  cellulose.  They  are 
chiefly  S'JP-  or  occasionally  even  gix.  in  diameter.  The  contents 
at  first  completely  fill  the  threads  and  consist  of  a  very  homo- 
geneous protoplasm,  or  this  may  also  contain  numerous  oil 
globules  of  varying  size.  As  the  threads  advance  in  their 
growth  they  often  become  empty  in  their  older  parts  and  also 
rarely  develop  septa  with  the  recession  of  the  protoplasm.  The 
writer  has  not  studied  the  special  haustorial  branches  that  push 
directly  into  the  cells  in  search  for  food,  and  Thaxter  simply 
states  that  the  mycelial  hyphae  rarely  penetrate  the  cells  of  the 
host  by  irregular  haustoria. 


DOWNY    MILDEW    OF   LIMA   BEANS.  28/ 

The  conidiophores  of  this  mildew  are  much  longer  than  those 
produced  by  the  potato  mildew.  In  the  figures  shown  here 
from  Thaxter,  Fig.  9,  ^®'  ^°'  the  young  conidiophores  have  not 
reached  their  full  length.  In  fact  they  usually  become  so  long 
and  lax  that  they  form  an  interwoven  mat  rather  than  erect 
distinct  threads.  They  also  differ  from  the  conidiophores  of 
the  potato  mildew  (which  give  off  two  to  several  simple 
branches  along  the  apical  third  of  their  length)  in  that  they  are 
simple  or  more  rarely  dichotomously  branched,  usually  near 
their  base.  Some  conidiophores  were  found  having  over  a 
dozen  swollen  nodes,  thus  indicating  the  formation  of  as  many 
spores,  but  usually  they  have  less  than  half  a  dozen,  which  may 
be  scattered  or  grouped  toward  the  terminal  end.  Occasionally 
it  is  difficult  to  detect  any  nodal  swellings  on  a  thread.  From 
these  statements  it  is  seen  that  the  conidiophores  are  not  so 
differentiated  into  spore-bearing  organs  as  in  the  potato  mil- 
dew. For  this  reason  it  is  hard  to  tell  whether  the  white 
matted  growth  that  covers  the  exterior  of  the  pods  is  com- 
posed entirely  of  conidiophores  or  partly  of  mycelium  from 
which  the  conidiophores  develop.  The  latter,  however,  are 
often  found  growing  directly  from  the  stomates  in  clusters 
which  sometimes  contain  a  dozen  individuals  but  more  fre- 
quently about  half  that  many.  Thaxter  does  not  give  the  length 
of  the  conidiophores  and  it  is  difficult  in  the  old  matted  groAvths 
to  separate  out  single  ones  for  measurements.  Specimens  were 
measured  that  varied  from  300  to  475 /a  but  these  were  pro- 
bably not  extreme  lengths.  In  an  examination  of  artificial 
cultures,  one  fruiting  thread  that  was  traced  measured  over 
1200/A  in  length.  The  diameter  of  the  conidiophores  is  usually 
about  5  or  6/x,,  rarely  8.5ft,  at  their  lower  end,  and  they  taper 
to  about  2.5  or  3ft  at  the  apical  extremity.  The  swollen  nodes 
generally  vary  from  4  to  6ft  in  width.  At  first  the  conidi- 
ophores are  filled  with  protoplasm,  but  as  spore  production  pro- 
ceeds their  contents  are  limited  to  the  distal  end  and  finally  they 
may  become  entirely  empty.  Their  walls  are  thicker  than  those 
of  the  mycelial  threads  and  give  a  stronger  reaction  in  the  test 
for  cellulose,  as  do  also  the  spore  walls.  Very  rarely  septa 
are  seen  in  the  empty  conidiophores. 

The  conidia,  or  spores,  of  the  Lima  bean  mildew.  Fig.  9,  ^^'  ^^' 
are  similar  to  those  of  the  potato  mildew,  but  larger.     The 


288        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

spores  of  the  latter  vary  from  17  to  35)U,  in  length  by  11  to 
20 fji  in  width,  while  those  of  the  Lima  bean  mildew  are  chiefly 
28  to  42 /a;  in  length  by  17  to  27/A  in  width,  and  Thaxter  records 
some  even  ^O/x  in  length.  They  are  hyaline,  elliptical  to 
chiefly  ovoid  in  shape  or  rarely  even  broadly  ovoid  to  subspher- 
ical.  The  papilla  of  dehiscence  is  very  evident  at  their  apical 
end,  and  when  shed  from  the  conidiophores  the  basal  end  is 
usually  marked  by  a  short  hyphal  plug  showing  the  point  of 
detachment.  Protoplasmic  contents  fill  the  spores  usually 
without  special  differentiation,  though  sometimes  at  germina- 
tion faint  areolations  appear. 

Germination  of  spores.  The  spores  do  not  germinate  readily 
unless  perfectly  fresh.  The  germination  of  such  spores  placed 
in  a  drop  of  water  in  a  Van  Tiegham  cell  takes  place  in  a  few 
hours  and  can  be  easily  watched  under  the  microscope. 
Thaxter's  excellent  description  of  their  germination  is  as 
follows : 

"The  germination  takes  place  in  two  ways.  In  the  one  case  a  single 
hypha  of  germination  is  produced,  which  may  enter  the  host  plant 
directly  or  give  rise  to  another,  or  secondary  spore  like  itself  (Fig.  9,  ^^' ^") 
which  germinates  in  its  turn  like  the  ordinary  conidia.  In  the  second 
case,  which  is  by  far  the  most  common,  the  content  of  the  spore  becomes 
very  faintly  lobular,  as  shown  in  Fig.  9,  '^  and  suddenly  and  rapidly 
begins  to  make  its  exit,  through  the  ruptured  apex  of  the  spore,  Fig.  9,  ^* 
.in  the  form  of  a  continuous  chain  of  spindle-shaped  bodies,  consisting 
of  naked  protoplasm;  the  orifice  alternately  expanding  and  contracting 
as  each  body  is,  as  it  were,  squeezed  out  by  the  pressure  from  within. 
In  some  cases  the  whole  content  of  the  spore  makes  its  exit  thus, 
the  chain  winding  itself  into  a  round  or  oval  mass  above  the  apex  of 
the  conidium  as  in  Fig.  9,  ^^.  Usually,  however,  the  chain  breaks  in  the 
course  of  its  discharge  and  almost  instantly  a  rapid  motion  begins,  at 
the  point  of  separation,  which  draws  the  spindle-shaped  bodies  suc- 
cessively apart.  The  motion  is  due  to  a  slender  thread  or  cilium,  drawn 
out  by  the  pulling  apart  of  the  narrow  zone  connecting  two  adjacent 
bodies,  and  the  rapid  vibration  of  this  thread  gives  rise  to  the  motion 
just  mentioned.  The  spindle-shaped  bodies,  as  soon  as  they  are  free, 
move  irregularly  for  a  moment,  changing  their  shape  the  while,  till  they 
become  contracted,  the  two  extremities  being  drawn  together  on  one 
side  towards  a  small  clear  spot,  usually  present  in  bodies  »of  this  nature, 
so  that  in  one  view  the  outline  is  slightly  crescent  or  bean-shaped 
(Fig.  9,^°).  After  or  during  this  change  of  shape  the  motion  of  the 
cilia  becomes  very  rapid,  and  the  bodies,  which  are  known  as  zoospores, 
dart  away  in  the  surrounding  water.  After  swarming  for  a  certain 
time,  usually  about  half  an  hour,  the  zoospores  come  to  rest,  assume  a 


DOWNY    MILDEW    OF   LIMA    BEANS.  289 

Spherical  shape,  swell  considerably,  become  surrounded  by  a  thin  cell 
wall  and  very  soon  begin  to  germinate  (Fig.  9, ")  by  giving  rise  to  a 
hypha  which  makes  its  way  into  the  tissues  of  the  host  plant,  thus 
infecting  it  with  the  disease.  The  whole  process,  owing  to  the  minute 
size  of  the  zoospores  which  are  less  than  lofo^w  of  an  inch 'in  diameter, 
may  take  place  upon  the  moist  surface  of  a  leaf  or  other  portion 
of  the  host  plant,  the  thinnest  pellicle  of  water  being  sufficiently  deep 
for  them  to  swim  in.  The  usual  number  of  zoospores  formed  from 
spores  of  average  size  is  about  fifteen,  so  that  each  spore  may  give  rise 
to  fifteen  distinct  points  of  infection."  , 

Perpetuation  of  the  fungus.  The  zoospores  just  described 
are  very  short  Hved,  lasting  so  far  as  known  but  a  few  hours. 
The  conidial  spores,  too,  are  of  a  temporary  nature,  retaining 
their  power  of  germination  but  a  comparatively  short  time  even 
under  favorable  conditions  and  in  dry  weather  perishing  in  a 
few  days  or  even  hours.  The  conidiophores  and  mycehum  are 
more  persistent,  but  as  the  Lima  bean  is  an  annual  it  is  impos- 
sible for  the  mycehum  to  live  over  the  winter  (except  in  the 
seeds)  as  a  dormant  parasite.  It  may  be  thought,  possibly, 
that  the  mycelium  survives  in  the  rubbish  of  the  diseased  beans 
and  in  the  spring  as  a  saprophyte  gives  rise  to  the  conidial 
spores.  This,  however,  is  contrary  to  the  known  habits  of  the 
downy  mildews  and  against  all  evidence  that  the  writer  can  find 
after  a  careful  examination  of  this  species.  Invariably  the 
Lima  bean  mildew  suffers  in  development  by  the  decay  of  the 
infected  pods  and  is  at  a  decided  disadvantage  in  competition 
with  bacteria  and  saprophytic  fungi  that  follow  in  its  wake. 
So  far  as  observed,  it  then  gradually  ceases  to  form  conidial 
spores  and  fails  entirely  to  spread  further,  at  least  in  this  spore 
stage.  If  the  mycelium  does  develop  as  a  saprophyte,  which 
we  doubt,  it  would  most  likely  produce  an  entirely  different  kind 
of  spores — the  oospores. 

Sturgis  made  some  observations  and  experiments  to  deter- 
mine if  the  mildew  survived  the  winter  in  the  refuse  of  a  mil- 
dewed crop  by  means  of  "resting  spores,  a  perennial  mycelium 
or  any  other  form."  In  his  search  through  such  material  that 
had  been  kept  out  doors  over  winter  he  failed  to  find  "any  trace 
of  a  vegetative  or  reproductive  body  which  could  be  even 
remotely  associated  with  the  Phytophthora  causing  the  mildew." 
Seeds  taken  from  this  refuse  and  planted  all  rotted  but  one. 
which  produced  a  perfectly  healthy  plant.    The  refuse  was  used 

19 


290        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

as  a  mulch  on  ground  at  the  Experiment  Station  and  planted 
with  Lima  beans,  but  the  beans  came  up  through  the  mulch  with- 
out apparent  infection  and  remained  free  from  the  mildew 
until  near  the  close  of  the  season,  when  some  did  appear.  In 
judging  of  the  results  of  this  experiment  one  must  remember 
that  Sturgis  found  no  sign  of  oospores  in  the  refuse  he  used 
and  presumably  they  did  not  occur  in  it  abundantly  if  at  all. 
The  writer,  however,  has  found  them  recently  under  similar 
conditions  though  mostly  in  poor  shape  due  to  attack  of  other 
fungi  on  them  before  they  were  matured.  It  must  be  taken 
into  account,  too,  that  the  mildew  did  appear  on  these  beans 
toward  the  end  of  the  season,  but  possibly  it  was  brought  in 
by  insects,  though  the  Experiment  Station  grounds  are  far  from 
any  other  place  where  Lima  beans  are  commonly  grown  and 
the  mildew  has  rarely  appeared  on  beans  planted  there.  Stur- 
gis evidently  considered  the  experiment  largely  a  failure 
because  "diseased  plants"  were  not  produced  from  diseased 
seed  and  because  the  mildew  did  not  appear  out  of  season  and 
in  abundance  from  primary  infections. 

In  a  preceding  paragraph  it  was  stated  that  as  the  Lima 
bean  was  an  annual  plant  it  was  impossible  for  the  parasitic 
mycelium  to  be  carried  over  from  one  year  to  another  by  it 
except  in  the  seeds.  We  believe  this  is  sometimes  done  and 
in  the  report  of  the  Station  for  1903,  p.  308,  expressed  the 
belief  that  it  was  the  ordinary  way  the  fungus  perpetuated 
itself.  From  our  examinations  of  the  past  year  we  now  know 
positively  that  the  mycelium  does  often  penetrate  from  the 
pods  into  the  seeds.  If  the  pod  is  badly  diseased  the  seeds 
are  destroyed,  or  at  least  injured  so  they  will  not  germinate, 
by  this  and  other  fungi  that  follow  it.  There  are,  however, 
probably  all  gradations  between  seeds  destroyed  and  those  in 
which  the  mildew  barely  gains  entrance.  Experiments  made 
by  the  writer  go  to  show  that  diseased  seeds  that  germinate  do 
not  produce  "diseased  plants" ;  that  is,  the  mycelium  does  not 
pass  from  the  seed  into  the  young  plant  and  produce  a  con- 
spicuously injured  plant  from  which  the  fungus  is  eventually 
spread  by  conidial  spores  to  other  plants.  There  is  reason, 
however,  for  believing  that  the  dormant  mycelium  may  be 
carried  over  the  winter  in  the  seeds  (just  as  is  the  potato 
mildew   in   the  tubers)    and  that   on  the  living  tissue   of  the 


DOWNY    MILDEW    OF   LIMA    BEANS.  2gi 

seed  when  planted  it  may  form  a  few  of  its  conidial  spores  (as 
can  the  potato  mildew  on  the  cut  surface  of  the  seed  tuber)  or 
that  possibly  in  some  cases  a  delayed  production  of  the 
oospores  takes  place  in  the  cotyledons.  In  either  case  the 
writer  believes  that  the  primary  infection  of  the  plants  takes 
place  by  the  germination  of  the  conidial  spores  or  the  oospores 
into  zoospores  and  these  latter  infect  the  parts  of  the  plant 
brought  into  contact  with  them  in  the  moist  earth.  That  the 
mycelium  is  sometimes  present  in  apparently  sound  seed  is 
shown  by  the  following  case,  in  which  nearly  matured  seeds 
were  taken  from  diseased  pods  in  the  fall  and  placed  in  a  damp 
chamber  on  moist  cotton.  These  seeds  were  taken  away  from 
the  diseased  part  of  the  pods  and  to  the  naked  eye  showed 
no  sign  of  disease  or  evidence  of  the  mildew.  Yet  in  less 
than  a  week  some  of  them  v/ere  developing  abundance  of 
oospores  in  their  tissues  and  some  few  had  a  slight  conidial 
development  on  the  outside.  The  only  point  not  determined 
was  how  long  the  mycelium  would  have  lived  had  the  seeds 
been  dried  out ;  or  in  other  words,  if  it  could  have  passed  the 
Vv'inter  in  them  and  then  have  gone  through  the  same  develop- 
ment when  they  were  planted  in  the  ground  in  the  spring. 

Mention  has  been  made  several  times  of  oospores.  Such 
spores  are  of  an  entirely  different  character  from  the  temporary 
conidial  spores.  They  are  thick- walled  and  are  usually  pro- 
duced by  the  mycelium  within  the  tissues  of  the  host.  They 
do  not,  as  a  rule,  germinate  when  formed  but  are  for  the  pur- 
pose of  carrying  the  fungus  over  the  unfavorable  winter  period 
and  on  germinating  the  next  season  produce  the  primary  infec- 
tions of  their  hosts.  Oospores  are  characteristic  of  the  downy 
mildews,  but  until  discovered  recently  by  the  writer  were  not 
known  for  the  Lima  bean  mildew.  Let  us  now  pass  to  a 
consideration  of  this  stage  of  the  fungus. 

OOSPORES,    OR    WINTER   STAGE. 

Where  and  when  found.  Although  Thaxter,  Sturgis  and 
the  writer  made  especial  search  for  the  oospores  they  escaped 
notice  until  September,  1905,  at  which  time  the  mildew  was 
unusually  abundant  in  the  region  of  New  Haven.  There  may 
be  two  reasons  why  the  oospores  were  not  found  before ; 
namely,   either  they   did   not   occur   commonly   or   they   were 


292        CONNECTICUT   EXPERIMENT   STATION    REPORT,    I905. 

not  looked  for  at  the  proper  place  and  time.  The  latter  reason 
more  likely  explains  the  failures  to  find  them.  Judging  from 
the  experience  of  the  past  year,  the  oospores  should  be  looked 
for  toward  the  end  of  the  season  and  in  the  seeds  of  the  pods 
badly  infected  with  the  mildew.  Sturgis  searched  especially 
for  them  in  the  pods  and  the  decaying  rubbish.  The  writer 
also  looked  for  them  chiefly  in  these  places  and  in  fact  actually 
collected  pods  in  1902  which  a  recent  examination  shows  had 
immature  oospores  in  the  seeds  that  escaped  detection.  Not 
all  of  the  seeds  from  infected  pods  contain  oospores  and  there 
is  no  sure  way  of  determining  whether  they  are  present  or  not 
except  by  microscopical  examination.  Often  after  the  myce- 
lium of  the  downy  mildew  penetrates  from  the  pods  into  the 
seeds,  the  mycelia  of  other  fungi,  especially  that  of  Fusa- 
rium,  develop  so  abundantly  as  to  seriously  interfere  with  the 
further  growth  of  the  Phytophthora.  Frequently,  too,  the 
mycelia  of  these  other  fungi  form  the  more  conspicuous  grov/th 
both  outside  and  inside  of  the  seeds.  Plate  XXI,  a,  shows  in  the 
lower  row  several  dried  seeds,  containing  oospores,  that  were 
taken  from  badly  mildewed  pods.  So  far  the  oospores  have 
been  found  in  the  seed  coats  and  cotyledons  of  the  seeds  and 
to  a  limited  extent  in  the  tissues  of  the  pods,  but  not  in  the 
leaves  or  the  stems. 

If  the  oospores  generally  occur  only  in  those  seasons  when 
the  mildew  is  unusually  abundant,  it  has  occurred  to  the  writer 
that  this  might  be  explained  on  the  supposition  that  there  exist 
two  mycelial  strains  of  the  fungus,  possibly  sexual  in  nature, 
and  that  the  production  of  oospores  can  only  result  when  these 
strains  occur  together  on  the  same  pods.  Naturally  a  season 
very  favorable  for  the  spread  of  the  fungus  would  multiply 
the  chances  of  these  occurring  together.  This  idea  of  dis- 
tinct mycelial  strains  is  discussed  further  in  this  report  in  the 
following  article  dealing  with  the  potato  downy  mildew,  where 
are  given  the  writer's  reasons  for  believing  that  such  strains 
may  exist  among  the  downy  mildews,  as  has  recently  been 
demonstrated  for  the  related  family  of  the  Mucoraceae. 

Description  of  oogonia,  etc.  The  downy  mildews,  or  the 
Peronosporeae  as  they  are  called  scientifically,  have  a  character- 
istic oosporic  stage  which  has  been  observed  for  many  of 
the  species  and  is  supposed  to  exist  for  all.     One  of  the  chief 


DOWNY    MILDEW    OF    LIMA    BEANS.  293 

functions  of  these  spores  is  to  carry  the  fungus  over  the 
unfavorable  winter  period.  The  oospores  differ  essentially  in 
structure  from  the  temporary  conidial  spores  in  that,  as  resting 
spores,  they  have  thick  walls,  and  are  formed  singly  inside 
•  a  special  envelope  called  the  oogonium,  and  further  differ  from 
them  in  origin  in  that  they  are  the  result  of  the  conjugation 
of  differentiated  sexual  branches  of  the  mycelium  developing 
usually  within  the  tissues  of  the  host.  The  male  cell  of  the 
mycelium  is  known  as  the  antheridium  and  after  its  contents 
are  emptied  into  the  special  female  cell,  the  oosphere  (immature 
oospore),  it  often  withers  away. 

The  characters  of  the  oogonia,  oospores  and  antheridia  of 
the  Lima  bean  mildew,  as  found  by  the  writer,  are  as  follows: 
Oogonia  (Plate  XX,  22-25)  inter-  or  intracellular  in  seed  coats 
or  cotyledons  of  seeds,  occasionally  in  tissues  of  pods  and 
more  rarely  imbedded  in  mycelium  on  surface  of  seeds  and 
pods,  with  rather  thin  scarcely  folded  walls  loosely  enclosing 
oospore,  at  first  hyaline  or  slightly  tinted  but  finally  reddish 
brown,  subspherical,  chiefly  23-38/1^  in  diameter.  Oospores 
(Plate  XX,  22-25)  spherical  or  sometimes  subspherical,  with 
apparently  smooth  and  moderately  thick  walls  (2.5-4)0,,  chiefly 
3/A  in  thickness),  hyaline  or  light  yellowish,  18-26;".,  chiefly 
19.5-22.5 /A  in  diameter.  Antheridia  (Plate  XX,  8,  9,  12- 17b) 
temporary,  hyaline,  variable,  sometimes  irregular  but  chiefly 
ovoid  to  ovate,  usually  applied  to  oogonia  near  their  place  of 
attachment  to  the  mycelium,  chiefly  8.5-11.5/*  in  width  by  14-17/x 
in  length. 

Development  of  oogonia,  etc.  It  is  not  easy  to  make  out 
exactly  the  stages  of  development  of  the  oogonia  even  from 
living  material.  This  is  because  the  mycelium  forms  a  matted 
growth  within  the  tissues,  often  obscuring  details.  The  very 
general  notes  given  here  were  obtained  partly  by  teasing  into 
fine  bits  pieces  of  the  seeds  known  to  contain  oospores  and 
exiamining  this  material  under  the  microscope  and  partly  from 
microscopic  examination  of  cultures  of  the  fungus  grown  on 
artificial  media  in  test-tubes,  though  some  fixed  and  stained 
sections  were  also  prepared  for  examination.  No  attempt  was 
made  to  study  the  cytological  phenomena.  Apparently  when 
the  oospores  are  to  be  formed  the  mycelium  becomes  more 
abundant  and  is  often  crowded  into  matted  growths  of  threads 


294        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I905. 

which  are  more  variable  and  irregular  iii  shape  than  normally. 
The  mature  oospores,  therefore,  are  likely  to  occur  more  thickly 
in  certain  places  rather  than  to  be  scattered  uniformly  in  the 
tissues  or  cultures.  So  far  as  could  be  determined  the  anthe- 
ridia  and  oogonia  are  developed  on  distinct  mycelial  threads. 
It  was  not  possible  to  trace  these  threads  far,  as  the  mycelium  by 
the  tearing  apart  is  more  or  less  torn,  but  also  it  becomes  less 
distinct  on  the  differentiation  of  these  organs,  through  loss  of 
contents.  These  fertile  threads  possibly  ultimately  have  origin 
on  a  common  mycelium,  but  more  probably  they  represent  dis- 
tinct mycelial  strains  mixed  together  whose  combined  presence 
is  necessary  for  the  production  of  oospores.  The  writer  is 
inclined  to  the  latter  view,  but  was  unable  to  determine  any 
very  distinctive  characters  by  which  an  antheridial  developing 
mycelium  can  be  told  from  that  bearing  oogonia,  if  such  really 
exist.  Very  often  the  mycelial  threads  had  swollen  places  in 
them  (Plate  XX,  4)  as  if  these  might  be  tentative  antheridia 
but  which  because  of  the  absence  of  oogonial  contact  had  run 
out  again  into  threads,  perhaps  developing  similar  swelling  fur- 
ther on.  It  seemed  to  be  true,  however,  that  the  antheridia  are 
not  usually  entirely  differentiated  on  the  thread  until  after  con- 
tact with  the  oogonium.  Likewise  there  were  not  found  many 
isolated  young  swollen  cells  that  represented  the  early  stages 
of  the  oogonia.  From  this  one  would  expect  that,  if  there  be 
distinct  strains,  their  mycelia  would  not  show,  when  grown 
separately,  any  development  of  antheridia  or  oogonian  but 
would  both  form  conidiophores.  This  would  agree  with 
DeBary's  statement  that,  'Tn  all  known  Peronosporeae  and 
Saprolegnieae  the  antheridia  are  not  formed  until  after  the 
extremity  of  the  branch  which  supports  them,  and  from  which 
they  are  afterward  separated  by  a  septum,  has  attached  itself 
to  the  oogonium  and  this  attachment  takes  places  in  the  early 
stage  of  both  organs." 

In  a  preceding  paragraph  the  mature  antheridia  were 
described.  They  are  formed  as  a  swollen  cell  (Plate  XX,  12b) 
at  the  end  of  a  mycelial  thread  or  a  short  mycelial  branch  as  cir- 
cumstances determine,  so  that  there  are  no  characteristic  anthe- 
ridial threads.  A  basal  septum  (Plate  XX,  14b)  soon  separates, 
the  swollen  end  of  the  mycelial  thread  into  a  distinct  terminal 
cell,  the  walls  of  which  remain  thin.     Usually  the  contents  of  the 


DOWNY    MILDEW    OF    LIMA    BEANS.  295 

antheridia  did  not  seem  to  be  so  sharply  marked  off  from  the 
cell  wall  as  those  of  the  oogonia,  often  appearing  empty 
because  of  this  lack  of  contrast.  This  was  probably  because 
oil  drops  are  not  so  prominent  a  constituent  as  in  the  oogonia. 
Often  after  the  antheridia  are  cut  off  the  threads  bearing  them 
are  empty  of  contents  and  difficult  to  trace  any  distance.  Some 
of  the  antheridia  showed,  when  isolated  from  the  oogonium, 
a  prominent  protuberance  (Plate  XX,  8)  but  nothing  was 
seen  like  a  distinct  fertilization  tube  which  penetrated  into  the 
oogonium  and  through  which  the  contents  were  emptied  into 
it,  as  has  been  described  for  some  species. 

The  oogonium  also  starts  as  a  swelling  (Plate  XX,  loc)  at 
the  end  of  a  mycelial  thread  or  a  short  branch  or  in  some  cases  is 
intercalary.  It  gradually  enlarges  and  assumes  a  subspherical 
shape.  It  is  thin-walled,  filled  with  protoplasm  and  oil  drops, 
and  after  empt}dng  the  thread  from  which  it  originates  of  the 
contents  is  separated  from  this  by  a  septum  (Plate  XX,  13c). 
Usually  before  the  oogonium  has  reached  large  size  a  young 
antheridial  branch  has  reached  it  and  the  antheridium  is 
formed  at  the  base  of  the  oogonium,  that  is,  where  it  is  joined 
to  the  mycelial  thread.  Soon  after  the  application  of  the 
antheridium  the  oogonium  reaches  full  size  and  a  further 
step  in  its  development  appears  in  the  transfer  of  its 
principal  contents  into  a  central  denser  mass,  the  ooplasm 
(Plate  XX,  15,  16),  which  a  less  conspicuous  marginal  peri- 
plasm surrounds.  This  central  ooplasmic  body  is  soon  further 
marked  off  by  the  formation  of  a  thin  limiting  wall  and  is  then 
known  as  the  oosphere  (Plate  XX,  19).  Though  not  observed, 
presumably  by  this  time  the  antheridial  contents  have  passed  into 
the  oosphere  by  means  of  a  fertilization  tube.  From  now  on 
the  contents  of  the  oosphere  show  changes  of  development  the 
character  and  sequence  of  which  were  not  definitely  made  out. 
At  the  same  time  the  wall  of  the  oogonium  becomes  slightly 
thicker  and  eventually  has  a  reddish  brown  tint.  The  periplasm 
does  not  seem  to  be  prominent  but  probably  assists  in  the 
formation  of  the  wall  of  the  oospore.  This  gradually  thickens 
until  2.5  or  3/A  thick  (Plate  XX,  22)  and  is  uniform,  smooth 
hyaline  or  slightly  yellowish  tinted  and  consists  of  a  single 
evident  layer,  but  outside  of  this  the  periplasm  apparently  forms 
an  amorphous  envelope  which  probably  serves  as  a  protection 


296        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

against  absorption  of  water  out  of  season.  A  large  oil  drop 
often  occupies  the  center  of  the  mature  oospore  and  this  is 
surrounded  by  a  dense  uniform  layer  of  protoplasm.  The 
oogonial  wall  permanently  invests  the  mature  oospore  (Plate 
XX,  23,  24)  as  a  loose  envelope,  but  all  signs  of  the  antheridium 
are  often  obliterated  by  this  time. 

Germination  of  oospores.  The  germination  of  the  oospores 
was  tried  several  times,  but  they  have  failed  to  germinate  up  to 
the  first  of  April  of  the  year  following  their  development.  The 
germination  of  spores  in  pure  cultures  left  out-doors  during 
the  greater  part  of  the  winter  will  be  tried  later,  since  they  too 
failed  to  germinate  as  early  as  April. 

Artificial  cultures.  This  is  the  first  time  the  downy  mildew 
of  Lima  beans  has  been  reported  as  grown  in  artificial  cultures, 
and  apparently  the  first  report  of  the  production  of  oospores 
of  any  mildew  in  cultures  of  this  character.  The  writer  has 
grown  the  downy  mildew  of  the  potato  in  artificial  cultures 
during  the  past  two  years  and  even  previous  to  this  two  French 
botanists  had  published  accounts  of  its  growth  under  similar 
conditions.  The  downy  mildew  of  tobacco  is  said  to  have  been 
grown  in  the  same  way.  Apparently  these  three  fungi,  all 
belonging  to  the  genus  Phytophthora,  are  the  only  species  of 
the  Peronosporeae  that  have  been  grown  in  this  manner. 

The  vigorous  development  of  the  Lima  bean  mildew  in  the 
fall  of  1905  suggested  that  perhaps  it  could  be  grown  on  various 
media  under  control  in  the  laboratory,  as  had  been  done  with 
the  potato  mildew.  As  certain  precautions  are  necessary  to 
secure  growths,  a  short  account  of  the  methods  are  given.  In 
the  first  place  a  culture  cannot  be  obtained  by  transference  of 
spore  material  to  a  test  tube  from  a  growth  on  the  pods.  This 
is  because  of  sure  contamination  with  other  fungi  or  bacteria 
which  will  stop  or  seriously  interfere  with  the  development  of 
the  comparatively  slow-growing  mildew.  Neither  can  cultures 
be  obtained  from  the  spores  by  the  Petrie  dish  separation 
method,  because  of  their  slow  growth  and  more  natural  germi- 
nation by  zoospores  instead  of  by  germ  tubes.  The  best  method 
for  securing  pure  cultures  is  to  transfer  into  the  culture  tubes 
pieces  of  the  tissue,  or  better  whole  seeds,  which  contain  myce- 
lium of  the  fungus,  taking  these  from  the  interior  of  pods  show- 
ing the  freshest  and  least  contaminated  external  growth  of  the 


DOWNY    MILDEW    OF   LIMA    BEANS.  29/ 

mildew.  Care  should  be  taken  in  breaking  or  cutting  open  the 
pods  and  a  sterilized  knife  or  forceps  are  necessary  to  remove 
the  tissue  or  seeds  from  the  interior.  The  first  attempts  seemed 
to  indicate  that  cultures  could  be  easily  obtained  in  this  way 
but  later  experience  showed  that  many  of  these  became  impure 
with  age.  Other  fungi,  especial  Fusarium,  closely  follow  the 
development  of  the  mildew,  and  unless  seeds  or  tissues  in  a  very 
early  stage  of  infection  are  selected  some  mycelium  of  these 
or  bacteria  will  also  be  included  and  eventually  spoil  the  cultures. 
In  the  test  tube  cultures  the  following  media  were  used: 
(i)  Living  beans  on  moist  cotton.  These  cultures  were  obtained 
in  two  ways,  (a)  Beans  were  taken  with  aseptic  precautions 
from  diseased  pods  and  placed  in  the  test  tubes.  As  these  beans 
were  usually  already  inoculated  with  the  mycelium  penetrating 
into  them  from  the  pod,  the  subsquent  development  of  the  fun- 
gus could  be  determined  by  examination  from  time  to  time, 
(b)  Beans  were  removed  from  perfectly  healthy  pods  with  the 
same  aseptic  care  and  after  placing  in  the  test  tubes  were 
inoculated  with  a  culture  of  the  fungus  or  tissue  from  a  diseased 
bean.  The  beans,  especially  the  (a)  cultures,  usually  formed 
a  more  or  less  evident,  though  not  luxuriant,  external  growth 
of  the  conidial  stage,  but  the  greatest  development  was  in  the 
production  of  oospores  within  the  tissues.  The  beans  generally 
turned  reddish  brown,  indicating  enzymal  action,  and  in  some 
cases  there  was  practically  no  external  growth  of  the  conidial 
stage.  Plate  XXI,  a*,  shows  a  bean  artificially  infected  in  which 
oospores  were  produced  abundantly  but  on  which  practically 
no  conidial  growth  occurred;  at  a**  is  shown  a  perfectly 
healthy  bean.  Most  of  the  successful  cultures  were  made  on 
these  living  beans,  as  there  was  less  interference  from  bacteria 
and  other  fungi  when  the  cultures  were  impure.  (2)  Steri- 
lized bean  tissues,  of  which  the  following  combinations  were 
tried ;  (a)  whole  beans  on  moist  cotton,  (b)  a  mixture  of 
ground  green  beans  and  pods,  and  (c)  a  combination  of  (b) 
the  corn  meal.  These  were  fairly  good  media,  but  bacteria, 
yeasts  and  fungi  bothered  considerably  if  they  were  not 
inoculated  with  perfectly  pure  material.  Both  the  conidial  and 
the  oogonial  stages  are  formed.  (3)  Agar  agar,  usually  made 
with  (a)  potato  juice  water  but  in  some  cases  (b)  with  sugar, 
and  peptone  and  certain  salts.     The  mildew  developed  poorly 


298        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O5. 

in  most  of  these  trials,  but  both  conidia  and  oogonia  occurred 
to  some  extent.  (4)  Corn  meal  which  was  made  up  with 
(a)  potato  juice,  (b)  peptone,  sugar  and  certain  salts,  and 
(c)  ground  beans  and  pods.  Corn  meal  is  a  good  medium 
when  once  the  fungus  gets  started,  and  in  these  trials  also  both 
stages  occurred.  Because  of  oogonial  production  the  fungus 
did  not  penetrate  as  deeply  into  the  medium  as  expected. 

Cultures  of  the  mildew  were  kept  going  from  the  middle  of 
September  to  the  middle  of  November.  At  first  there  was  a 
more  luxuriant  growth  of  the  conidial  stage  than  toward  the 
end  of  the  period  and  finally  this  stage  seemed  to  so  run  out 
that  it  was  practically  impossible  to  continue  cultures.  At 
all  times  it  was  easier  to  start  cultures  from  inoculated  tissue 
than  from  tufts  of  the  fungus  transferred  by  needle  from  one 
tube  to  another.  There  was  required,  too,  a  certain  degree  of 
moisture  in  the  culture  to  insure  the  best  growth.  By  far 
the  best  results  were  obtained  on  the  living  bean  cultures. 
Fungi,  bacteria  and  yeast  bothered  considerably,  especially  on 
the  sterilized  media.  It  was  very  difficult  to  get  cultures  that 
did  not  finally  develop  such  impurities,  though  a  number  of 
these  were  obtained.  The  growths  of  the  Lima  bean  mildew 
were  in  marked  contrast  with  those  obtained  of  the  potato  mil- 
dew in  that  the  development  of  the  conidiophores  was  incon- 
spicuous while  the  reverse  is  true  in  nature.  No  doubt  the 
formation  of  oospores  greatly  interferes  with  the  conidial  devel- 
opment, and  if  this  latter  could  have  been  secured  alone,  as  it 
was  with  the  potato  mildew,  a  much  more  luxuriant  external 
growth  would  have  been  made.  One  of  the  most  interesting 
questions  connected  with  the  cultures  of  these  two  mildews  is 
why  in  one  case  oospores  were  always  produced  and  never  in 
the  other.  This  question  is  discussed  more  fully  in  the  follow- 
ing article  on  the  potato  mildew. 

PREVENTIVE    MEASURES. 

From  the  preceding  discussion  one  can  see  that  there  are 
certain  conditions  that  favor  the  introduction  and  spread  of  the 
mildew  in  the  Lima  bean  fields.  Some  of  these  factors  can 
be  controlled,  at  least  to  a  certain  extent,  by  the  grower.  In 
the  following  paragraphs  are  given  briefly  the  means  by  which 
he  may  hope  to  prevent  or  lessen  the  injury  inflicted  by  this 
parasite. 


DOWNY    MILDEW    OF    LIMA    BEANS.  299 

Selection  of  seed.  It  has  been  shown  how  the  dormant 
mycelium  and  the  oospores  carr}'  the  fungus  over  from  one' 
year  to  another  in  the  seed.  If  possible,  therefore,  the  seed 
should  be  gathered  from  a  field  entirely  free  from  the  disease. 
Where  this  is  impossible  a  very  careful  selection  should  be  made 
from  pods  that  show  no  sign  of  the  mildew  and  from  these 
onl}^  the  best  and  least  shriveled  should  be  used. 

Rotation.  It  will  do  no  good  to  select  disease-free  seed  if 
this  is  planted  on  land  that  bore  a  diseased  crop  the  year  before, 
as  the  old  seed  rotting  in  the  soil  will  probably  furnish  oospores 
for  infection.  Each  year  the  beans  should  be  planted  on  a 
different  piece  of  ground,  so  that  three  or  four  years  pass  before 
it  is  again  used  for  this  crop.  This  is  a  practice  not  always 
followed,  as  one  large  grower  in  the  state,  at  least,  has  planted 
beans  year  after  year  on  the  same  land  and  his  beans  are  sure 
to  be  attacked  by  the  mildew  if  any  are  that  year. 

Destruction  of  rubbish.  Where  rotation  is  faithfully  fol- 
lowed each  year  perhaps  little  good  will  be  accomplished  by 
destroying  the  old  vines,  as  the  oospores  probabh^  will  not  live 
in  the  ground  more  than  a  year  or  two.  Where,  however,  the 
grower  deems  it  very  essential  to  use  the  same  land  the  next 
year  for  Lima  beans,  the  chances  for  infection  will  probably  be 
lessened  by  gathering  and  burning  in  the  fall  all  of  the  rubbish 
of  the  old  crop.  It  should  be  borne  in  mind  in  this  work  that 
the  pods  and  seeds  are  the  parts  it  is  most  necessary  to  destroy. 

Methods  of  planting,  etc.  The  Lima  beans  are  usually 
planted  to  climb  upright  poles  and  these  are  set  in  rows  to  allow 
cultivation  in  one  direction.  They  should  be  set  a  sufficient  dis- 
tance apart  in  the  rows  (sa}'  three  to  three  and  a  half  feet)  and 
the  rows  should  be  of  sufficient  width  (about  four  and  a  half 
feet)  to  allow  free  entrance  of  the  "sunshine  to  dry  off  the  foli- 
age and  prevent  the  enclosed  air  from  being  too  damp.  Neither 
should  more  than  two  or  three  vines  be  grown  to  a  pole  for  the 
same  reason.  Low  moist  spots  in  the  field  favor  the  first  infec- 
tions and  the  spread  of  the  mildew  afterwards,  so  it  is  desirable 
if  such  exist  to  plant  some  other  crop  on  these  spots.  So,  too, 
considering  injury  from  the  mildew  only,  it  is  more  advanta- 
geous to  use  a  high  dry  field  than  a  lower  more  moist  one. 

Spraying.  Sturgis  is  the  only  investigator  who  has  reported 
spraying  experiments  for  the  prevention  of  this  mildew.     His 


300        CONNECTICUT   EXPERIMENT   STATION    REPORT,    I905. 

first  experiments  were  made  in  1893  with  a  number  of  fungi- 
cides, but  as  the  mildew  did  not  appear  in  this  field  even  on 
unsprayed  vines  no  conclusions  could  be  drawn,  except  that  the 
fungicides  did  not  injury  the  foliage  in  any  case.  In  1897  he 
made  further  trials  using  Bordeaux  mixture,  ammoniacal  solu- 
tion of  copper  carbonate,  potassium  sulphide,  and  sulphur  as 
the  fungicides.  The  best  results  were  obtained  with  a  row 
that  was  sprayed  three  times  with  Bordeaux  and  twice  with 
Amm.  Sol.  Cop.  Car.,  as  this  yielded  296  marketable  pods 
against  25  on  an  adjacent  unsprayed  tow.  Sturgis  says,  "The 
conclusion  to  be  drav/n  from  this  experiment  is  that  even  in  a 
season  most  favorable  to  the  Lima  bean  mildew,  thorough  treat- 
ments of  the  vines  with  the  Bordeaux  mixture  will  ensure  a 
crop." 

While  the  writer  has  conducted  no  spraying  experiments  for 
the  prevention  of  this  mildew,  he  has  watched  certain  fields  in 
the  vicinity  of  New  Haven  that  have  been  sprayed.  From  these 
observations  and  the  results  of  Sturgis'  work  the  following  sug- 
gestions are  offered:  Spraying  need  not  be  commenced  before 
the  middle  of  July,  or  possibly  in  very  wet  seasons  about  the 
first  of  this  month.  Bordeaux  mixture  is  the  most  satisfactory 
fungicide  and  in  later  sprayings  need  not  be  replaced  by 
Ammo.  Sol.  of  Cop.  Car.  or  potassium  sulphide  if  the  market- 
able pods  are  picked  before  each  spraying.  Even  if  some  sedi- 
ment does  still  adhere  to  the  pods  when  picked,  this  can  do 
no  possible  injury  unless  prejudice  militates  against  their  sale. 
The  spray  should  be  directed  chiefly  to  the  young  parts  of  the 
vines  and  should  be  delivered  in  a  fine  mist.  It  is  most  import- 
ant that  the  spray  reach  the  pods  and  least  important  that  the 
foliage  be  covered.  Three  or  four  thorough  sprayings  with 
Bordeaux  mixture  will  probably  be  sufficient  for  most  seasons. 
Most  of  the  spraying  observed  by  the  writer  has  been  partially 
ineffectual  because  it  was  done  too  early  in  the  season  and 
because  the  leaves  were  the  parts  chiefly  protected. 

Factors  beyond  control.  Season  is  the  chief  factor  in  deter- 
mining the  amount  of  injury  by  the  mildew.  As  stated  before, 
very  wet  weather  from  July  to  September  is  favorable  for  the 
development  of  the  trouble.  Of  course  the  weather  can  not 
be  controlled,  but  where  one  has  taken  the  preceding  precau- 
tions his  loss  should  be  much  less  than  one  who  has  not.     A 


DOWNY    MILDEW    OF    LIMA    BEANS.  3OI 

second  factor  not  under  control  is  insect  visitation.  As  shown 
by  Sturgis,  bees  may  spread  the  disease  in  a  field  and  we  have 
reason  to  believe  that  they  may  carry  it  to  a  certain  extent  from 
one  field  to  another.  This  being-  the  case,  one  who  makes  the 
preceding  precautions  to  keep  the  disease  out  of  his  field  should 
also  isolate  it,  as  far  as  possible,  from  other  fields,  especially 
from  those  that  are  likely  to  be  seriously  troubled.  Where  the 
fields  are  very  close  together  not  only  insects  but  also  the  wind 
may  help  to  carry  the  disease  from  one  to  another. 

EXSICCATI. 

Specimens  of  the  Lima  bean  mildew  have  been  issued  in  the 
following  exsiccati,  all  the  specimens  having  been  collected  in 
the  vicinity  of  New  Haven  on  Phaseolus  lunatus:  Seym.  & 
Earle  Eco.  Fungi,  9  (Thaxter,  Sept.  Oct.,  1889)  ;  Ellis  &  Ev. 
N.  A.  F.,  2707  (Thaxter,  Sept.,  1890)  ;  Bri.  &  Car.  Fung.  Par., 
351  (Rorer,  Sept.,  1901)  ;  Ell.  Ev.  Barth.  Fungi  Col.,  1949 
(Clinton,  Aug.  29,  1902). 

LITERATURE. 

The  following  references  to  the  literature  of  this  mildew 
include  all  of  any  importance  that  the  writer  has  been  able  to 
find.  Even  some  of  these  contain  only  data  taken  from  Thaxter 
and  Sturgis. 

1.  Berlese,  A.  N.    Phytophthora  Phaseoli  Thaxt.     Riv.   Pat.  Veg.,  9: 

41-4.     1902. 

Gives  scientific  description  and  general  notes  on  this  fungus, 
which  he  lists  only  from  New  Haven,  Conn.,  drawing  his  data 
from  Thaxter  and  Sturgis. 

2.  Briosi,    G.   and   Cavara,   F.     Phytophthora   Phaseoli   Thaxt.    Fung. 

Par.  No.  351.     [Illustr.] 

Issue  specimens  from  New  Haven  collected  by  Rorer  and  give 

figures  and  descriptions  taken  from  Thaxter. 

3.  Clinton,    G.    P.      Downy  Mildew,    Phytophthora    Phaseoli    Thaxt. 

Ann.  Rep.   Conn.  Agr.  Exp.   Stat.,   1903:    307-8.     1904.     [Illustr.] 
Gives  short  general  account  of  the  fungus  and  suggestions  for 
its  prevention. 

4.  Halsted,    B.   D.     Notes   upon   Mildew   of   Lima   Beans.     Ann.    Rep. 

N.  J.  Agr.  Exp.  Stat,  1897:  297-9.     1898.     [Illustr.] 

Reports  this  very  serious  in  Bergen  Co.,  N.  J.,  in  1897 ;  mildew 
worst  on  low  land  that  had  Lima  beans  on  it  the  year  before. 


302        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

5.  Halstead,  B.  D.     The  Phytophthora  of  Lima  Beans.    Bull.  Torr.  Bot. 

Club,  25:    161-2.     1898.     [Illustr.] 

Notes  this  fungus  as  serious  in  New  Jersey  in  1897,  which  was 
a  wet  season. 

6.  Halsted,    B.    D.      Late    Growth    of    Bean    Mildew — Phytophthora 

Phase oli  Thaxt.     Bull.  Torr.  Bot.  Club,  26:    20.     1899. 

Notes  late  growth  of  the  fungus,  Oct.  24,  on  the  green  pods 
after  the  leaves  had  been  killed  by  frost. 

7.  Halsted,  B.  D.     The  Downy  Mildew  of  Lima  Beans.     Bull.   N.  J. 

Agr.  Exp.  Stat.,  151 :    18-24.     1901.     [Illustr.] 

Gives  a  general  account  of  this  fungus,  which  has  proved  a 
serious  trouble  of  Lima  beans  in  New  Jersey  in  wet  seasons. 

8.  Halsted,  B.  D.     The  Mildew  of  Lima  Beans.     Ann.  Rep.  N.  J.  Agr. 

Exp.  Stat.,  1902:    399-403.     1903.     [Illustr.] 

Reports  troublesome  in  New  Jersey  in  1902  and  gives  extracts 
concerning  it  from  Bull.  151  of  the  New  Jersey  Station. 

9.  Jaczewski,   A   de.     Phytophthora  Phaseoli.     Bull.   Torr.    Bot.   Club, 

29:   649.     1902. 

Salmon  quotes  portions  of  a  letter  from  above  botanist,  who 
notes  presence  of  this  fungus  in  Russia. 

10.  Orton,  W.  A.     Phytophthora  Phaseoli  Thaxt.     Yearbook  U.  S.  Dep. 

Agr.,  1903:    554.     Ibid.,  1904:    584. 

Lists  the  fungus  as  injurious  in  Connecticut,  New  Jersey  and 
Delaware  in  1903;  but  in  1904  it  is  reported  only  from  New 
Jersey. 

11.  Saccardo,  P.  A.    Phytophthora  Phaseoli  Thaxt.     Sacc.  Syll.  Fung., 

9:   341.     1891. 

Gives  scientific  description  taken  from  Thaxter  and  lists  only 
from  New  Haven,  Conn. 

12.  Smith,  C.  O.     Mildew  of  Lima  Bean.     Bull.   Dela.  Agr.  Exp.,  63: 

23-4.     1904. 

Deals  briefly  with  this  fungus  and  notes  its  appearance  in 
Delaware  from  July  on  in  1903. 

13.  Speschnew,  N.  N.     Les  parasites  vegetaux  de  la  Cakhetie.  Arb.  Bot. 

Gart.  Tiflis,  lief.  2,  1897.     [Review:    Zeitsch.  Pflanzenk.,  11:    113.] 
Lists    Phytophthora    Phaseoli    Thaxt.    from    the    Gouvr.    Tiflis 
(Kaukasus). 

14.  Sturgis,  W.   C.     Mildew   of   Lima  Beans.     Ann.   Rept.   Conn.   Agr. 

Exp.  Stat.,  1893:   77.     1894. 

Used  several  fungicides  but  as  the  fungus  was  not  present  in 
the  sprayed  field  their  value  was  not  determined. 

15.  Sturgis,  W.  C.     The  Mildew  of  Lima  Beans  (Phytophthora  Phaseoli 

Thaxt.).     Ann.   Rep.   Conn.  Agr.  Exp.   Stat.,   1897:    159-66.     1898. 
[Illustr.] 

Gives  a  general  account  of  the  fungus  and  shows  how  bees 
spread  the  fungus  to  the  flowers ;  gives  results  of  successful 
spraying  experiments   with   Bordeaux  mixture,   etc. 


DOWNY    MILDEW    OF    LIMA   BEANS.  3O3 

16.  Sturgis,  W.  C.     On  some  aspects  of  Vegetable  Pathology  and  the 

Conditions  which  influence  the  Dissemination  of   Plant  Diseases. 
.  Bot.  Gaz.,  25:    191-4.     1898.     [Illustr.] 

Shows  how  insects  and  wind  are  influential  in  the  spread  of 
Phytophthora  Phaseoli. 

17.  Sturgis,   W.    C.     Mildew   of   Lima    Beans.     Ann.    Rep.    Conn.   Agr. 

Exp.   Stat.,  1898:    236-41.     1899. 

Made  experiments  to  determine  efifect  of  thin  and  thick  planting 
an  upright  and  slanting  poles  on  amount  of  mildew,  which  was 
very  bad  this  season ;  looked  especially  for  means  by  which  it 
carried  over  winter  in  old  rubbish  but  found  nothing. 

18.  Thaxter,    R.      A    new    American     Phytophthora.      Bot.     Gaz.,     14: 

273-4.     1889. 

Gives  a  general  and  a  scientific  description  of  this  new  species, 
Phytophthora  Phaseoli  Thaxt. 

19.  Thaxter,    R.      Mildew    of    Lima    Beans    -{Phytophthora    Phaseoli 

Thaxt.).     Ann.  Rep.  Conn.  Agr.  Exp.  Stat.,  1889:    167-71.     1890. 
[Illustr.] 

Includes  a  general  description  of  the  fungus,  an  account  of  its 
germination,  its  relation  to  other  species  and  methods  for  its  pre- 
vention. 

20.  Thaxter,  R.     Mildew  of  Lima  Beans.     Ann.  Rep.  Conn.  Agr.  Exp. 

Stat,  1890:   97-8.     1891. 

Notes  distribution  of  fungus  in  Connecticut,  especially  during 
this  year. 

21.  Thaxter,   R.     Phytophthora  Phaseoli  Thaxt.     Journ.   Myc,  7:    279. 

1893. 

Gives  scientific  description  and  references  to  literature  of  this 
fungus. 


304        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

DOWNY  MILDEW,  OR  BLIGHT,  Phytophthora  infestans 
(Mont.)    DeBy.,   OF   POTATOES.     II. 

In  the  Report  of  this  Station  for  1904  the  writer  gave  the 
first  installment  of  his  work  with  the  potato  blight.  This 
included  a  short  general  account  of  the  life  history  of  the 
fungus,  so  far  as  known,  and  of  spraying  experiments  looking 
toward  the  most  practical  methods  for  controlling  the  disease. 
The  investigations  of  the  past  year,  reported  in  this  article, 
have  been  made  chiefly  to  determine  more  minutely  and  accu- 
rately points  in  the  life  history  of  the  fungus  in  the  hope  that 
when  this  is  definitely  and  completely  known,  prevention  of  its 
ravages  will  be  an  easier  task  to  those  who  take  advantage  of 
this  knowledge.  The  points  that  need  especial  elucidation  are 
the  way  or  ways  by  which  the  fungus  first  infects  the  vines  in 
the  summer  (that  is  the  primary  infections),  its  history,  if  any, 
in  the  soil,  and  the  means  by  which  it  is  carried  over  from  year 
to  year.  To  gain  such  information  the  writer  made  careful 
observations  of  the  very  first  appearance  of  the  disease  in 
various  fields,  examined  the  plants  and  tubers  in  all  conditions 
of  health  and  decay,  carried  on  indoor  inoculation  experiments 
and  grew  the  fungus  in  artificial  culture  for  two  years.  We 
are  not  yet  satisfied  with  what  is  known  of  the  fungus  and  hope 
later  to  make  additional  reports  concerning  it. 

Primary  Infections. 

Diseased  plants.  What  conditions  do  the  very  first  infec- 
tions of  the  year  in  a  given  region  or  field  require?  We  know 
that  the  disease  has  never  appeared,  or  at  least  has  never  been 
recorded,  in  Connecticut  before  the  first  week  of  July,  and 
sometimes  it  is  not  found  before  the  middle  of  August,  and 
that  the  more  rainy,  cloudy  and  foggy  these  months  are  the 
quicker  it  gets  a  start  and  the  more  rapidly  it  spreads.  Smith 
and  DeBary  also  report  that  the  blight  is  seldom  seen  in 
Europe  before  July  or  August,  though  rarely  it  has  been  found 
oven  in  May  or  June.  The  common  belief,  or  at  least  the  one 
advocated  by  DeBary  concerning  the  advent  of  the  fungus  in  a 
field,  is  that  it  comes  from  "diseased  plants." 

Perhaps  DeBary's  (2)  views  can  be  best  shown  by  the  follow- 
ing quotation:     "The  facts  which  have  been  observed  estab- 


DOWNY    MILDEW    OF    POTATOES.  305 

lish  that  there  are  two  methods  by  which  the  conidia  may 
pass  from  the  tuber  to  the  foliage.  First,  it  is  known  that 
the  mycelium  of  the  fungus  in  the  tuber,  even  when  in  the 
ground,  is  able  to  produce  conidiophores  bearing  conidia 
directly  from  the  tuber.  We  can  easily  see  how  the  conidia 
thus  produced  could  reach  the  foliage — they  might  be  carried 
up  either  by  the  growing  plant  which  may  have  touched  them, 
or  by  small  animals  which  frequent  both  situations.  Neither 
of  these  methods  can  be  easily  detected.  Moreover,  the  forma- 
tion of  conidia  in  the  soil  cannot  be  very  frequent.  There 
should  therefore  perhaps  be  little  weight  attached  to  this 
method.  The  second  method  can  be  easily  observed  and  with 
great  exactness.  It  consists  in  the  mycelium  growing  from  the 
tubers  in  and  with  the  3^oung  plants  and  producing  conidia  on 
them  in  the  usual  way;  and  these  [diseased  plants!]  of  course 
extend  the  fungus  to  the  healthy  plants  beside  them.  In  1861 
I  called  attention  to  the  fact  that  tubers  containing  Phytophthora 
when  they  are  growing,  not  unfrequently  send  out  shoots  into 
which  the  fungus  passes  from  the  tubers.  The  fungus  advanc- 
ing slowly  in  its  growth  at  last  kills  the  shoots,  which  for  the 
most  part  were  always  in  a  sickly  condition.  The  same  tubers, 
as  is  known,  may  also  send  out  healthy  shoots  at  the  same  time. 
I  further  showed  that  under  special  circumstances  the  fungus 
in  these  diseased  shoots  develops  conidia.  These  were  not 
conjectures,  but  facts  observed  in  experiments.  The  observa- 
tions, however,  were  not  made  in  the  open  field,  but  in  the  house 
and  laboratory,  and  had  not  been  confirmed  by  myself  or 
observed  by  others  in  the  open  field."  DeBary  tried  to  demon- 
strate this  second  theory  by  planting  tubers  he  infected  through 
the  eyes  outdoors  along  with  healthy  ones,  and  obsersdng  if, 
upon  the  growth  of  the  plants,  the  disease  spread  to  the  leaves 
of  all  the  plants.  In  his  first  trial,  although  he  grew  a  diseased 
plant,  the  fungus  never  fruited  on  this  and  so  did  not  spread 
the  disease.  In  the  second  trial  the  healthy  and  diseased  tubers 
were  planted  out  early  in  the  garden  in  a  box  and  several 
diseased  shoots  appeared  which  in  time  developed  a  fruiting 
condition  of  the  fungus,  so  that  before  the  end  of  May  the 
blight  had  spread  to  many  of  the  leaves  of  all  of  the  plants. 
This  was  long  before  its  appearance  elsewhere  in  the  neighbor- 
hood. 

20 


306        CONNECTICUT   EXPERIMENT    STATION    REPORT,    IQOS- 

The  writer,  thinking  that  DeBary's  "diseased  plants"  might 
offer  the  best  explanation  of  the  first  appearance  of  the  blight, 
made  special  search  for  them  in  different  fields  after  the  vines 
were  above  ground  at  various  times  up  to  the  general  appearance 
of  the  disease,  but  was  not  successful  in  finding  such  plants. 
True,  one  sometimes  finds  plants  stunted  by  the  bacterial  stem 
rot  and  also  those  with  cankered  areas  on  the  parts  below  ground 
caused  by  the  Rhizoctonia  fungus,  but  no  sign  of  any  disease 
like  or  unlike  these  containing  outbreaks  of  the  blight  fungus. 
For  two  or  three  years  efforts  also  have  been  made  in  the  green- 
house to  produce  blight  diseased  plants  from  tubers  known  to 
contain  the  mycelium  of  the  blight  fungus.  The  badly  diseased 
tubers  often  failed  entirely  to  grow ;  others,  less  diseased,  pro- 
duced plants,  sometimes  making  a  poorer  growth  than  usual, 
but  never  showing  any  signs  of  the  blight.  Thinking  that 
possibly  the  greenhouse  conditions  were  not  favorable  for  deter- 
mining this  point,  as  the  atmosphere  there  was  usually  rather 
dry,  a  more  extended  experiment  was  conducted  outdoors  in 
the  spring  of  1905.  Through  the  kindness  of  some  thirty 
Connecticut  potato  growers  who  had  suffered  from  rot  of 
tubers  in  1904,  a  few  potatoes  showing  disease  were  obtained 
from  each.  While  these  growers  were  requested  especially  for 
tubers  showing  the  reddish  superficial  rot  characteristic  of 
blight,  the  potatoes  sent  showed  the  Rhizoctonia,  scab,  and 
Fusarium  rot  troubles  as  much  or  more  than  they  did  the  blight. 
The  tubers  were  divided  into  five  lots  and  planted  in  five  rows, 
as  follows :  ( i )  tubers  freest  from  disease,  also  treated  with 
formalin;  (2)  same  as  (i)  but  not  treated;  (3)  tubers  badly 
scabbed;  (4)  tubers  with  abundance  of  Rhizoctonia;  (5) 
tubers  with  Fusarium  or  blight  rots,  or  both.  In  the  last  case 
some  of  the  tubers  were  badly  rotted  and  the  plants  in  this  row 
came  up  somewhat  slower  and  less  uniformly  than  in  the  others, 
but  there  were  no  blight  diseased  plants  seen  at  any  time  and  the 
first  blight  that  appeared  was  on  leaves  of  a  plant  in  the  row 
whose  tubers  had  been  selected  as  freest  from  disease  and  then 
treated  with  formalin !  Neither  did  the  tubers  produce  any 
more  rot  in  the  fifth  row  than  those  in  the  other  rows,  while 
the  row  of  scabby  tubers  produced  a  crop  badly  scabbed  and 
the  Rhizoctonia  row  one  with  that  trouble  very  prominent. 
Other  experimenters  (Smith,  DeBary)  have  also  reported  cases 


DOWNY    MILDEW   OF   POTATOES.  307 

in    which    perfectly    sound    plants    were    grown    from    blight- 
diseased  tubers. 

The  only  instance  in  which  the  writer  has  seen  anything  like 
a  blight-diseased  plant,  as  recorded  by  DeBary,  was  in  the  green- 
house, where  a  healthy  tuber,  planted  in  a  crock  with  the  top 
just  above  the  surface  of  the  soil,  was  inoculated  with  the  blight 
fungus  on  one  of  the  young  buds,  which  was  then  covered  with 
moist  cotton  and  a  small  bell  jar.  This  bud  was  finally  killed 
and  the  reddish  brown  rot  of  the  blight  extended  in  time  down 
into  the  tissues  of  the  tuber  about  a  quarter  of  an  inch  and 
spread  for  some  distance  beneath  the  skin,  reaching  another 
eye  from  which  eventually  was  grown  a  stem  several  inches 
long.  This  stem,  see  Plate  XXIV,  b,  about  thirty  or  forty  days 
after  the  inoculation  showed  a  reddish  brown  discoloration  on 
the  exterior  from  the  base  to  the  tip  and  the  conidial  spores  of 
the  blight  fungus  were  produced  sparingly  upon  it.  The  inte- 
rior tissues  of  the  stem,  however,  seemed  to  be  perfectly  healthy 
and  free  from  the  fungus,  and  so  if  the  disease  came  from  the 
mycelium  in  the  tuber  growing  up  into  the  stem,  this  growth 
occurred  in  the  external  tissues  rather  than  through  the  bundles, 
as  one  might  expect.  There  was  a  possibility,  even  in  this  case, 
that  the  disease  was  inoculated  externally  by  lice  carrying 
spores  from  the  inoculated  place  on  the  tuber,  since  perfectly 
healthy  stems  grew  out  of  the  sides  of  this  diseased  one.  So 
far  as  the  writer  can  judge  from  reports  in  literature  and  his 
own  experience,  DeBary's  "diseased  plant"  method  of  primary 
infection  does  not  seem  to  have  sufficient  support  so  far  to  jus- 
tify the  belief  that  it  is  the  common  method  in  nature. 

Contact  of  leaves  with  ground.  But  if  the  blight  does  not 
generally  first  spread  from  a  diseased  plant,  how  does  it  start  in 
a  field?  There  is  offered  here  an  explanation  which  our  obser- 
vations of  the  past  year  seem  to  indicate  as  the  ordinary  method 
of  infection.  Possibly  this  idea  has  been  advanced  before, 
since  the  writer  has  not  carefully  examined  the  literature  to 
determine  this  point.  In  support  of  our  observations  that  the 
blight  does  not  usually  start  from  diseased  plants,  let  us  first 
quote  the  following  from  Smith  (6,  p.  293)  :  "It  is  obvious 
that  if  the  potato  disease  is  annually  reproduced  by  diseased 
tubers  containing  perennial  mycelium,  the  disease  must  invaria- 
bly begin  in  the  seed  tuber  and  ascend  the  stem ;  but  it  is  known 


308        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

b}^  experience  that  in  the  vast  majority  of  instances  this  is  not 
the  case,  but  that  the  disease  first  invades  the  leaves."  This 
corresponds  with  our  observations  of  the  past  summer ;  namely, 
that  the  disease  first  appeared  on  a  few  leaflets,  often  on  the 
outermost  leaves,  of  the  fully  grown,  perfectly  healthy  plants, 
and  these  conditions  of  its  appearance  preclude  the  belief  that 
the  disease  came  by  the  mycelium  in  the  diseased  tubers  ascend- 
ing the  stems  and  growing  out  into  the  leaves,  all  without  caus- 
ing any  injury  or  evidence  of  its  presence  until  finally  it 
produced  the  characteristic  black  spots  on  the  isolated  leaflets! 
But  Smith  does  not  state  definitely  how  the  disease  came  on 
the  leaflets  in  these  cases.  We  believe  it  comes  by  contact  of 
the  leaves  with  the  ground  at  the  critical  ivet  periods  of  July  and 
August  zvhen  the  germs  of  the  blight  are  probably  first  generally 
available  in  the  soil  for  infection,  and  that  this  is  the  ustial 
method  of  primary  infections  in  the  fields. 

In  support  of  the  preceding  statement  we  give  the  following 
evidence:  The  season  of  1905  was  dry  during  midsummer,  so 
the  blight  was  backward  in  its  appearance.  A  number  of  fields, 
chiefly  in  the  vicinity  of  New  Haven,  were  examined  from  time 
to  time  tO'  note  the  very  first  signs  of  blight.  Weather  favorable 
for  this  trouble  came  on  about  August  9th  to  the  i6th  and  the 
first  blighted  leaves  found  anywhere,  August  nth,  were  in  an 
isolated  field  at  Southington  that  had  not  been  examined  before. 
This  field  of  two  or  three  acres  had  been  in  potatoes  the  year 
before  but  was  greener  and  in  a  better  condition  than  many 
fields  at  this  time,  as  the  drought  and  other  agents  had  been 
very  injurious.  After  a  careful  search  of  the  field  the  attempt 
to  find  any  blighted  leaves  was  about  to  be  given  up  when  two 
plants  near  together  were  found  on  which  a  dozen  leaflets 
showed  a  single  blight  spot  each.  Two  of  these  leaflets  were 
still  in  contact  with  the  moist  ground  and  half  of  the  others 
showed  by  the  dirt  on  them  that  they  had  recently  been  in  con- 
tact with  the  soil.  Of  course  it  is  possible  that  some  of  these 
spots  may  have  come  from  secondary  infections,  as  the  fungus 
was  already  fruiting  on  these  leaves.  There  was  no  sign  of  a 
diseased  plant  in  the  field  so  far  as  observed  and  certainly  none 
in  the  vicinity  of  the  outbreak,  and  an  examination  of  the  two 
plants  having  the  diseased  leaflets  showed  no  sign  of  the  fungus 
on  their  stems.     The  later  development  of  the  blight  in  this 


DOWNY    MILDEW    OF    POTATOES.  3O9 

field  was  not  observed.  The  second  place  where  the  blight 
was  found  was  on  August  12th,  in  the  small  isolated  plat  at  the 
Experiment  Station,  previously  mentioned,  where  the  tubers 
showing  different  kinds  of  disease  were  planted.  In  this  case 
they  were  in  sod  land  that  had  not  been  in  potatoes  before.  The 
plat  was  carefully  watched,  so  that  a  diseased  plant  could  not 
have  escaped  observation.  Here,  too,  no  such  plant  occurred 
and  the  blight  first  appeared  on  a  healthy  plant  which  had 
about  ten  leaflets  with  single  blight  spots,  in  fruiting  condition, 
when  found.  Two  of  these  leaflets  were  still  in  contact  with 
the  soil  and  two  thirds  of  them  showed  dirt  on  their  under 
surface,  indicating  recent  contact  with  it.  There  were  no  out- 
breaks anywhere  on  the  stem  of  this  plant  or  even  on  the  parts 
below  the  ground  so  far  as  could  be  observed.  The  disease 
afterward  gradually  appeared  throughout  the  plat.  The  third 
case  found  was  in  an  isolated  field  of  half  an  acre  in  Whitney- 
ville,  by  which  the  writer  often  passed  and  stopped  to  look  for 
the  blight.  This  was  first  found  August  i6th,  when  after  a 
careful  search  a  plant  was  discovered  with  a  single  leaf  showing 
the  blight.  While  this  leaf  was  then  off  from  the  ground,  the 
dirt  on  its  under  side  again  showed  recent  contact  with  it.  A 
photograph  of  this  leaf  is  shown  in  Plate  XXIII,  a;  only  the 
badly  diseased  leaflet  was  producing  conidial  spores.  No  sign 
of  the  blight  was  found  on  any  other  part  of  the  plant,  though 
looked  for  carefully.  In  a  second  place  in  the  field,  but  removed 
from  this,  another  plant  was  found  with  several  blight  spots  on 
the  leaves,  some  of  which  were  still  in  contact  with  the  ground. 
Here  the  blight  had  spread,  in  some  cases,  from  the  blades  onto 
the  pedicles  and  petioles,  but  these  were  always  near  the  blight 
spots  and  all  of  the  petioles  were  perfectly  free  from  the  disease 
at  their  base.  There  was  again  absolutely  no  sign  of  the  fun- 
gus on  the  stem  of  the  plant.  Later  the  blight  gradually  spread 
over  the  field.  Other  fields  examined  up  to  this  time  had  shown 
no  blight,  but  by  the  22d  of  August  it  was  found  appearing 
generally  in  a  number,  so  that  from  this  time  on  the  disease 
was  not  uncommon  in  fields  still  green. 

Planting  potatoes  zvithout  rotation.  It  is  not  an  uncommon 
practice  for  farmers  in  this  state  to  grow  potatoes  two  consec- 
utive years  on  the  same  land  and  there  is  at  least  one  field  in  the 
vicinity  of  New  Haven  that  has  had  potatoes  on  it  for  several 


3IO        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

years  in  succession.  While  the  writer  has  not  yet  determined 
from  his  own  observations  whether  the  fungus  can  carry  over 
the  winter  in  the  old  tubers  in  the  soil,  Massee  (3)  of  England 
makes  the  following  very  definite  statement:  "I  have  observed 
the  important  fact  that,  when  the  diseased  potatoes  are  planted, 
after  the  crop  has  been  lifted,  the  remains  of  the  old  seed  pota- 
toes when  brought  to  the  surface  of  the  ground  will  produce 
a  crop  of  the  fungus  bearing  myriads  of  spores.  If  such  old 
seed  potatoes  are  kept  buried  in  soil  until  the  following  year 
and  then  exposed  to  light,  under  favorable  conditions,  fungus 
fruit  is  still  produced,  and  continues  to  grow  so  long  as  a  scrap 
of  the  old  potato  remains.  I  have  now  in  the  laboratory  at 
Kew  Gardens  scraps  -of  last  year's  seed  potatoes  covered  with 
the  fungus,  and  with  the  spores  thus  produced  have  success- 
fully inoculated  the  leaves  of  young  potato  plants."  If  Massee's 
statement  is  true,  then  fields  used  two  years  in  succession  should, 
as  a  rule,  develop  the  blight  earlier  and  spread  it  more  rapidly 
than  fields  not  in  potatoes  before  for  some  time.  As  the  writer 
knew  of  three  fields  which  had  produced  a  badly  diseased  crop 
the  year  before  and  were  used  again  last  year  for  potatoes, 
these  were  examined  to  see  if  this  was  so.  The  one  most  care- 
fully watched  was  in  Westville  and  had  abundant  rotten  tubers 
from  the  preceding  crop  left  on  it.  In  this  case,  however, 
the  vines  were  practically  dead  before  any  blight  appeared  in 
the  neighborhood,  so  that  all  that  could  be  determined  was  that 
its  use  a  second  year  did  not  cause  an  unusually  early  appear- 
ance of  blight  in  it.  The  other  two  fields  were  at  Green's 
Farms  and  so  could  not  be  watched  so  closely.  When  first 
examined  on  August  19th  they  both  showed  blight  more  promi- 
nently than  other  fields  in  the  neighborhood.  This  was  espe- 
cially true  of  the  earlier  plant  field,  in  which  the  blight  was 
very  prominent,  while  another  field  on  the  same  farm  isolated 
from  this,  but  on  land  not  in  potatoes  for  years,  was  at  this 
time  practically  free  from  blight — only  a  single  blighted  leaf 
being  found  there.  On  August  28th  at  Hamden  a  fourth  field 
was  examined  that  was  said  to  have  had  potatoes  on  it  several 
years  in  succession,  and  this  showed  more  blight  in  it  than  had 
been  seen  in  any  field  up  to  that  time  in  the  vicinity  of  New 
Haven.  Other  fields  examined  generally  showed  an  earlier 
or  a  more  vigorous  start  of  the  blight  if  they  had  been  in  pota- 


DOWNY    MILDEW    OF    POTATOES.  3  I  I 

toes  the  year  before.  We  do  not  wish  to  state  positively,  from 
these  observations,  that  the  blight  starts  earlier  and  more  vigor- 
ously in  a  field  that  bore  a  blight-diseased  crop  the  year  before, 
as  such  factors  as  situation  of  the  land,  earhness  of  planting, 
etc.,  may  need  consideration  here,  but  so  far  as  they  go  they 
seem  to  point  to  this  conclusion. 

Secondary  Infections. 

By  secondary  infections  are  meant  all  those  that  take  place 
from  and  after  the  original  infections  (the  outbreaks  on  a 
diseased  plant,  if  such  exists,  or  on  leaves  infected  from  con- 
tact with  the  ground),  and  thus  generally  spread  the  disease 
to  the  leaves  of  these  plants,  to  those  throughout  the  field  or 
even  to  other  fields.  The  means  cited  here  (rain,  wind,  and 
insects)  have  usually  been  considered  agents  for  the  distribution 
of  the  blight  spores,  though  few  special  observations  have  been 
published  showing  them  to  be  such  or  indicating  how  far  the 
disease  may  be  carried  by  them.  To  determine  these  points 
more  fully  the  following  observations  and  experiments  were 
made  the  past  year. 

Rain.  The  testimony  of  all  who  have  written  concerning 
blight  shows  that  rainy  or  moist,  muggy  weather  is  absolutely 
essential  to  the  development  and  spread  of  blight  in  the  fields. 
This  is  especially  necessary  for  this  fungus  because  the  spores 
on  germination  usually  form  swimming  spores,  zoospores, 
which  are  the  common  agents  of  infection.  Not  only  is  moist 
weather  necessary  for  infection,  but  dry  bright  weather  follow- 
ing the  infection  largely  stops  the  spread  and  even  the  devel- 
opment of  the  fungus  already  within  the  leaves.  The  moist 
blackened  tissues  then  dry  up,  and  though  the  disease  may  seem 
to  have  suddenly  caused  great  damage,  it  is  not  progressing 
into  the  healthy  green  tissues  beyond  as  it  would  have  done  had 
the  weather  remained  moist.  Rain  not  only  induces  the  for- 
mation and  germination  of  the  spores,  but  it  serves  as  an  agent 
in  distributing  them. over  the  infected  plants  and  also  washes 
them  down  into  the  soil  to  the  tubers.  It  can  not  of  course  be 
of  much  service  in  carrying  spores  from  one  plant  to  another 
unless  they  overlap,  and  therefore  by  itself  could  only  very 
slowly  spread  the  disease  throughout  a  field  if  there  had  been 
but  a  single  starting  point. 


312        CONNECTICUT    EXPERIMENT   STATION    REPORT,    I905. 

Wind.  It  is  not  so  easy  to  prove  that  wind  serves  as  a  means 
of  distribution,  but  it  no  doubt  acts  as  a  carrying  agent  of  the 
spores  to  vines  in  the  same  field  or  to  fields  situated  closely 
together.  The  fungus,  however,  is  not  especially  adapted  for 
dispersal  by  the  wind,  since  the  spores  are  borne  on  the  under 
side  of  the  leaves  and  on  the  whole  are  not  produced  in  great 
abundance.  The  dry  winds  of  bright  weather  would  be  of 
little  value,  as  it  is  in  such  weather  that  the  spores  rapidly  lose 
their  power  of  germination  and  would  find  least  opportunity 
for  germination,  even  if  carried  into  a  field.  It  does  not  seem 
likely,  therefore,  that' wind  is  a  common  agent  in  carrying  the 
spores  from  one  isolated  field  to  another.  The  case  cited  in  a 
previous  paragraph — the  field  the  second  year  in  potatoes  at 
Green's  Farms  in  which  blight  developed  vigorously  and  early — 
seems  to  indicate  that  wind  may  be  a  prominent  agent  of  dis- 
persal for  short  distances,  since  the  prevailing  winds  were  from 
the  direction  of  the  infected  field  toward  an  adjoining  one, 
which  also  soon  became  infected  with  the  blight. 

Insects.  Apparently  insects  are  a  common  agent  in  the  dis- 
tribution of  the  spores  throughout  a  field,  and  the  chief  means 
of  conveying  them  from  one  field  to  another  somewhat  remote. 
In  other  words,  if  it  were  not  for  insects,  the  selection  of  an 
isolated  field  which  had  not  been  used  recently  for  growing 
potatoes  and  which  was  planted  with  tubers  free  from  the 
disease  should  give  a  crop  exempt  from  blight.  The  most 
common  insects  in  the  potato  fields  of  Connecticut  are  the  flea 
beetle  and  the  common  potato  bug,  or  Colorado  beetle.  The 
latter  is  well  adapted  for  carrying  spores,  since  the  under  side 
of  the  tarsi  of  the  legs,  especially  the  third  tarsus,  is  provided 
with  a  stiff  brush  of  hairs  that  would  easily  retain  spores  tem- 
porarily as  the  insect  crawled  over  an  infected  leaf.  The  only 
insect  examined  to  determine  this  point  did  not  actually  have 
the  spores  of  the  blight  fungus  on  the  brushes  of  hairs,  but 
these  did  have  spores  of  other  fungi,  showing  they  could  serve 
such  a  purpose.  The  soft,  somewhat  moist  body  of  the  larvae 
of  the  potato  beetle,  too,  possibly  aids  in  distributing  the  spores. 
Just  how  helpful  to  the  fungus  the  flea  beetles  are  in  this  work 
is  not  known. 

To  determine  whether  insects  could  carry  the  blight  from 
one  isolated  field  to  another,  an  experiment  was  conducted  last 


DOWNY    MILDEW    OF    POTATOES.  313 

year  at  Mr.  Burr's  place  near  Green's  Farms.  The  potatoes 
were  planted  in  a  garden  on  soil  that  had  not  contained  potatoes 
for  at  least  five  years.  The  garden  was  isolated  and  well  sur- 
rounded by  trees,  etc.,  and  was  not  situated  so  that  wind  would 
blow  from  another  field  toward  it.  The  nearest  potatoes  were 
at  least  an  eighth  of  a  mile  awa}^  and  the  badly  diseased  field 
mentioned  before,  about  half  a  mile.  The  seed  tubers  were 
obtained  from  Colorado  on  the  recommendation  of  Mr.  Orton 
of  the  Division  of  Vegetable  Pathology  of  Washington  that 
this  was  a  region  of  the  United  States  exempt  from  blight.  So 
far  as  could  be  learned,  the  grower  of  these  potatoes  had  never 
been  troubled  with  this  disease  and  Professor  Paddock  of  the 
Colorado  Experiment  Station  writes  that  he  has  never  identified 
the  blight  in  that  state.  These  potatoes  were  examined  the 
same  time,  August  19th,  that  the  writer  looked  through  the 
other  fields  on  Mr.  Burr's  farm.  After  a  searching  examina- 
tion a  couple  of  leaves  showing  the  blight  were  found,  and  Mr. 
Burr  wrote  in  the  fall  that  eventually  these  potatoes  suffered 
from  the  blight  about  as  badly  as  the  others.  Without  much 
question  the  potato  bug  was  the  means  of  introducing  spores 
for  the  first  infection,  after  which  the  blight  spread  from  this 
throughout  the  plot.  Part  of  the  Colorado  potatoes  were 
planted  on  land  not  recently  in  potatoes,  but  very  close  to  the 
badly  blighted  field  mentioned  before,  and  these  on  August  19th 
showed  considerable  blight  on  the  leaves.  Both  the  wind  and 
insects  were  no  doubt  the  carrying  agents  here.  Some  potato 
seed  was  also  obtained  from  this  Colorado  grower  and  planted 
in  the  greenhouse  during  the  winter  and  the  young  seedlings 
set  out  later  on  the  Experiment  Station  grounds  about  five 
rods  from  ordinary  garden  potatoes.  These  seedlings,  too, 
became  infected  with  the  blight,  but  not  until  sometime  after 
it  appeared  on  the  garden  potatoes.  The  potato  bug  was  again 
the  most  probable  carrying  agent.  From  this  experience,  the 
writer  concludes  that  the  grower  can  not  depend  upon  isolation 
of  a  field  and  absolute  freedom  of  soil  and  tubers  from  the 
fungus  to  secure  a  crop  free  front  blight  since  insects  are  very 
likely  to  carry  in  the  disease,  though  the  more  isolated  the  field 
the  less  likelihood  of  infection.  Such  conditions,  however, 
will  insure  a  later  appearance  of  the  blight  in  the  field,  but 
whether  retarding  the  invasion  will  prove  of  any  practical  value 


314        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

will  depend  upon  how  long  the  infection  is  delayed  and  the 
weather  conditions  thereafter. 

Artificial  Infections. 

By  this  is  meant  indoor  infections  produced  by  the  writer, 
chiefly  with  pure  artificial  cultures  of  the  blight  fungus.  To 
secure  infection  it  is  necessary  that  the  cultures  be  in  fresh 
spore-producing  condition  and  that  the  inoculated  plants  be 
kept  moist  or  in  a  moist  atmosphere,  not  only  during  the  infec- 
tion period,  but  also  afterwards  if  the  fungus  is  expected  to 
appear  in  its  fruiting  stage  on  the  surface  of  the  infected  parts. 
The  few  experiments  tried  were  made  to  determine  how  easily 
infection  takes  place  under  different  conditions  and  how  soon 
the  conidial  stage  appears  after  the  spores  are  applied.  Both 
leaves  and  tubers  were  used  as  subjects  for  infection. 

With  the  leaves.  DeBary  showed  that  the  germ  tubes  of  the 
zoospores  of  potato  blight  can  enter  the  leaves  either  through 
the  stomates  or  by  penetrating  directly  through  the  epidermis. 
The  usual  method  in  the  latter  case  is  for  the  germ  tube  to 
push  its  way  down  between  the  walls  where^  two  cells  come 
together  and  then  grow  down  into  the  intercellular  spaces  of 
the  leaf  beneath,  but  DeBary  also  observed  cases  in  which  the 
germ  tubes  bored  directly  into  the  epidermal  cells  themselves. 
The  ability  of  the  fungus  to  gain  entrance  in  these  various  ways 
greatly  aids  its  spread  over  its  hosts.  The  stomates  are  more 
numerous  on  the  under  surface  of  the  leaf,  but  most  of  the 
infections  probably  take  place  from  the  upper  surface,  as  the 
spores  are  most  likely  to  be  carried  here  from  the  conidio- 
phores  borne  on  the  under  surface  of  leaves  above. 

In  our  infection  experiments  after  the  spores  were  placed  on 
the  upper  surface  of  the  young  leaves,  usually  by  the  end  of 
three  days  it  could  be  determined  if  the  inoculation  was  suc- 
cessful by  the  slight  discoloration  of  the  tissues.  By  the  end 
of  the  fourth  day  this  discoloration  was  more  evident  and 
conidiophores  were  beginning  to  protude  through  the  stomates, 
and  by  the  end  of  the  fifth  day  the  diseased  spot  was  well 
marked  and  a  few  mature  conidiophores  and  conidial  spores 
were  present.  As  these  spores  can  germinate  immediately,  sec- 
ondary infections  could  take  place  within  five  days  after  the 
primary.     Perhaps  the  development  of  the  fungus  can  be  shown 


DOWNY    MILDEW    OF    POTATOES.  315 

best  by  a  detailed  account  of  the  infection  of  the  plant  shown 
in  Plate  XXIV,  a,  which  was  photographed  ten  days  after  the 
spores  were  applied.  Its  history  is  as  follows :  January  nth, 
placed  spores  in  water  on  three  lower  leaves,  covered  each  with 
a  small  piece  of  moist  cotton  and  the  plant  with  a  small  bell  jar. 
January  14th  (3  days),  the  two  lower  leaves  showed  slight  dis- 
coloration at  points  where  spores  were  placed.  January  i6th 
(5  days),  the  spots  were  well  marked  and  conidiophores  and 
spores  were  formed  in  small  numbers,  January  i8th  (7  days), 
about  two  thirds  of  the  two  lower  leaves  were  plainly  diseased 
(yellowish,  limp  and  partly  blackened)  and  the  conidiophores 
were  developing  over  the  greater  part  of  this  area,  but  most 
abundantly  on  lower  surface  ;  two  diseased  streaks  showed  on  the 
stem  but  had  few  conidiophores  on  them ;  petiole  of  one  leaf 
was  covered  with  conidiophores,  but  showed  little  discoloration. 
January  21st  (10  days,  see  illustration),  the  two  lower  leaves 
were  dead  and  hanging  limp ;  the  third  leaf  showed  yellowish 
discoloration  over  apical  half  and  was  producing  conidiophores ; 
the  fourth  leaf  (apparently  a  secondary  inoculation  by  lice) 
had  a  few  conidiophores  on  it,  but  no  injury  to  its  tissues  showed 
as  yet;  several  blackish  streaks  showed  on  the  stem  where  the 
fungus  had  gained  a  foothold  from  the  diseased  leaves  above. 
With  the  tubers.  There  are  a  number  of  different  conditions 
under  which  inoculation  of  the  living  tissues  of  the  tubers  may 
be  tried ;  namely,  on  the  cut  surface  in  a  moist  atmosphere,  on 
various  uninjured  parts  (eyes,  buds,  skin)  before  or  after 
removal  of  the  tuber  from  the  plant,  or  on  these  same  places 
after  mechanical  injury  to  them.  In  the  experience  of  the 
writer  the  development  of  the  fungus  varies  greatly  under  these 
dissimilar  conditions.  It  grows  most  luxuriantly,  at  least  exter- 
nally, on  the  cut  surface  of  the  tuber  in  a  moist  atmosphere. 
Before  inoculation  it  is  always  desirable  to  soak  the  whole  tuber 
in  a  2  per  cent,  formalin  bath  for  half  an  hour  and  to  use  a  ster- 
ilized knife  in  cutting  it,  in  order  to  limit  as  much  as  possible  the 
development  of  other  fungi  and  bacteria  which  easily  crowd  out 
the  Phytophthora.  Discoloration  of  the  tissues,  at  least  for 
some  time,  does  not  follow  the  development  of  the  fungus  on 
the  cut  surface  of  the  tuber ;  this  probably  indicates  very  super- 
ficial penetration  into  the  tissues. 


3l6        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

DeBary  states  that  he  secured  infection  of  the  tubers  very 
readily  through  the  terminal  eyes.  Presumably  the  buds  were 
slightly  developed  in  the  tubers  he  used.  Our  experiments, 
at  least,  seemed  to  indicate  that  it  is  very  much  easier  to  secure 
successful  inoculation  through  the  very  young  buds  than  it  is 
at  the  eyes  of  a  perfectly  dormant  tuber  in  which  no  bud  is  yet 
evident.  These  experiments,  too,  go  to  show  that  inoculations 
on  the  uninjured  skin  of  a  dormant  tuber  are  not  likely  to  be 
successful,  while  at  the  same  spot  if  the  skin  is  first  injured 
by  a  knife  puncture  the  inoculation  succeeds.  Likewise,  in  the 
single  experiment  tried,  the  inoculations  were  not  very  success- 
ful on  the  uninjured  skin  of  very  young  tubers  still  attached  to 
the  plant,  and  scarcely  more  so  when  the  tissues  were  injured 
before  inoculation.  Possibly  some  of  these  results  were  partly 
due  to  the  age  of  the  cultures  used,  but  even  then  there  seems 
to  be  no  doubt  that  there  is  greater  variability  and  difficulty  in 
securing  infection  of  the  tubers  than  of  the  leaves. 

Three  of  these  inoculation  experiments  with  the  tubers  are 
recorded  here:  i,  November  ipth,  tried  to  inoculate  five  dor- 
mant tubers,  using  artificial  cultures  of  the  blight.  Each  tuber 
was  buried  in  the  soil  of  a  crock  so  that  a  single  lateral,  deeply 
indented  eye,  showing  no  sign  of  bud  formation,  was  exposed 
above  the  surface  of  the  soil.  These  uninjured  eyes  served 
as  a  cavity  into  which  the  spores  and  water  were  placed,  when 
they  were  then  covered  with  watch  crystals  lined  with  moist 
paper  to  retain  the  moisture.  The  tubers,  however,  were  so 
thoroughly  seasoned  that  the  water  in  the  eyes  was  rapidly 
absorbed  and  had  to  be  replaced  many  times  during  the  next 
few  days,  though  the  soil  around  the  tubers  was  also  kept  moist. 
Possibly  this  dying  out  influenced  the  result,  for  not  a  single 
inoculation  was  effective,  and  at  the  end  of  32  days  the  tubers 
were  still  perfectly  sound  at  these  eyes.  2,  December  21st, 
used  the  same  tubers  but  placed  the  spores  away  from  the  eyes 
on  a  small  spot  where  the  skin  had  been  injured  by  a  knife. 
On  examination  ten  days  later  rots  showed  at  all  of  the  points 
of  puncture.  Some  of  these  were  the  characteristic  dry  reddish 
brown  rot  of  the  Phytophthora,  with  or  without  the  conidio- 
phores  showing  slightly  at  the  punctured  point,  while  in  other 
cases  bacteria  were  also  agents  of  the  decay.  January  9th  one 
of  the  tubers  was  half  rotted  and  a  short  shoot  from  it  had  been 


DOWNY   MILDEW    OF    POTATOES.  31/ 

killed  by  Phytophthora  and  bacteria,  having,  apparently,  become 
inoculated  externally  by  lice.  February  21st,  took  up  all  of  the 
tubers  and  the  plants  that  had  developed  from  them.  All  of 
the  seed  tubers  were  entirely  rotted,  showing  more  or  less  of 
the  characteristic  reddish  brown  dry  rot  of  the  Phytophthora, 
especially  near  the  outside,  but  all  but  one  had  produced  plants 
and  small  tubers.  None  of  these  new  tubers  showed  any  sign 
of  rot;  neither  were  any  of  the  plants  diseased.  Cross  sec- 
tions of  the  stems  close  to  the  old  seed  tubers  and  of  the  under- 
ground shoots  running  from  these  to  the  new  tubers  in  no  case 
showed  any  sign  that  the  mycelium  of  the  blight  fungus  had 
passed  or  was  passing  from  the  diseased  tubers  into  these,  j, 
February  21st,  inoculated  four  young  tubers  (about  one  inch 
in  diameter,  growing  in  greenhouse  bench)  with  culture  of  the 
blight  fungus, — two  with  and  two  without  injury  to  tissues. 
February  23d  the  injured  spots  showed  evident  but  very  slight 
rot,  while  the  uninjured  showed  doubtful  start.  March  20th 
the  injured  spots  had  rotted  but  little,  being  only  ^  of  an  inch 
in  diameter  and  extending  but  slightly  into  the  flesh ;  while 
the  uninjured  spots  were  only  about  ^  of  an  inch  in  diameter 
and  still  more  superficial.  The  fungus  did  not  fruit  at  any  of 
these  places  and  bacteria  may  have  been  partially  responsible 
for  the  rot,  though  in  the  case  of  the  check  tuber,  injured  but 
not  inoculated,  no  rot  appeared. 

Artificial  Cultures. 

So  far  as  known  to  the  writer,  the  reports  of  Matruchot  and 
MolHard  (4,  5)  made  in  1900  and  1903  are  the  only  ones  so  far 
published  concerning  pure  artificial  cultures  of  the  blight  fun- 
gus. The  work  reported  here  was  begun  in  the  fall  of  1904, 
before  learning  of  the  investigations  of  these  French  botanists, 
and  has  been  carried  on  now  for  about  two  years.  Growth  of 
the  fungus  on  various  media  in  test-tubes  was  undertaken 
chiefly  to  see  if  this  would  not  throw  some  new  light  on  the 
life  history  of  the  fungus,  especially  with  regard  to  the  missing 
oospores.  The  general  results  obtained  agree  with  those  of 
the  French  investigators,  though  the  details  of  methods  and 
media  used  were  not  altogether  the  same. 

Hozv  obtained.  Pure  cultures  of  the  blight  fungus  are  not 
so  easily  obtained  as  are  those  of  many  fungi,  since  because  of 


3l8        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I905. 

their  slow  growth  they  are  easily  crowded  out  in  competition 
with  other  fungi,  and  because  the  ordinary  Petrie  dish  separation 
method  is  not  available  with  their  spores,  which  prefer  a  fluid 
medium  for  germination.  Matruchot  and  Molliard  apparently 
made  most  of  their  cultures  by  exposing  the  cut  surface  of  an 
infected  tuber  in  a  moist  chamber  until  the  fungus  ran  out  on 
this  in  its  fruiting  stage,  when  material  from  the  growth  was 
transferred  by  a  sterilized  needle  to  test  tubes  containing  various 
media.  Such  growths  on  the  tubers  are  nearly  always  contami- 
nated_and  usually  only  a  few  of  the  cultures  made  from  them 
remain  pure.  If  the  tubers  are  first  sterilized  on  the  outside 
by  a  bath  in  formalin  and  cut  with  a  sterilized  knife,  better 
results  will  be  obtained.  It  is  desirable,  too,  if  possible,  to  use 
only  tubers  showing  a  superficial  decay  of  the  Phytophthora 
rot.  On  the  whole,  the  writer  was  most  successful  in  obtaining 
cultures  when  the  reddish  brown  diseased  tissue  from  the  inte- 
rior of  a  tuber  next  the  healthy  tissue  was  removed  in  small 
pieces,  about  a  third  of  an  inch  in  diameter,  by  a  sterilized  knife 
and  then  inserted  on  the  medium  in  the  test  tube.  In  this  case 
the  mycelium  from  the  diseased  tissue  in  time  runs  out  onto 
the  medium  and  often  produces  a  pure  growth  of  the  fungus. 
Where  infected  tubers  are  not  available  for  cultural  work,  the 
fungus  can  be  started  on  the  freshly  cut  surface  of  a  sterilized 
tuber  by  suspending  over  it  a  leaflet  containing  a  vigorous, 
fresh  outbreak  of  the  blight.  The  spores  falling  on  the  cut 
surface  soon  start  a  growth  of  the  fungus,  from  which  material 
may  be  transferred  to  the  test  tubes.  Here,  too,  contamina- 
tions usually  prevail  in  spite  of  precautions.  Plate  XXIII,  b, 
shows  a  nearly  pure  growth  of  the  fungus  started  in  this  way. 
One  of  the  most  common  fungous  interlopers  is  a  species  of 
Fusarium  and  it  is  often  impossible  to  distinguish  between  the 
growths  of  this  and  the  Phytophthora  and  they  soon  become 
intermingled.  Microscopical  examination  is  usually  necessary  to 
determine  which  part  of  the  growth  on  the  cut  surface  of  the 
potato  presents  the  blight  fungus  in  a  pure  condition. 

Media,  Appearance,  etc.  Altogether  twenty-five  to  thirty 
different  cultural  media  and  modifications  of  the  same  medium 
were  tried  to  determine  the  most  satisfactory  ones  and  also 
to  see  if  the  fungus  could  be  induced,  under  different  conditions, 
to  develop  any  unknown  stage.     These  media  fall  in  four  gen- 


DOWNY    MILDEW    OF    POTATOES.  3I9 

eral  classes;  viz.,  i.  Plugs  of  living  plant  tissue,  2.  Sterilized 
plant  products,  3.  Agar  agar  media,  4.  Earth  and  manure. 
The  results  are  discussed  briefly  in  the  following  paragraphs. 

1.  The  writer  found,  as  did  Matruchot  and  Molliard,  that 
plugs  of  living  tissue  taken  with  antiseptic  precautions  from 
the  interior  of  a  potato,  and  to  a  less  extent  from  the  pumpkin, 
offered  a  very  favorable  medium  for  the  growth  of  the  fungus. 
These  plugs  were  cut  from  the  interior  of  a  sterilized  tuber  with 
a  knife,  which  had  been  sterilized  with  heat  and  allowed  to  cool 
so  as  not  to  sear  the  tissue,  and  after  slicing  off  the  sides  a  sec- 
ond time  were  placed  in  the  test  tubes  on  a  sterilized  cushion 
of  cotton  saturated  with  water.  With  proper  care  these  plugs 
can  usually  be  obtained  free  from  organisms  and  if  the  atmos- 
phere of  the  tube  is  kept  sufficiently  moist  upon  inoculation  the 
mildew  forms  a  very  favorable  growth.  This  is  more  or  less 
luxuriant,  apparently,  according  to  the  conditions  of  moisture 
and  the  success  with  which  the  original  infection  took  place. 
Sometimes  a  scanty  growth  of  normal  conidiophores  producing 
numerous  spores  occurs  or  again  a  conspicuous  pure  white  felt 
develops,  of  which  a  large  part  is  made  up  of  mycelial  threads. 
Plate  XXV,  a,  shows  (b)  a  rather  scanty  and  (c)  a  very  luxuri- 
ant growth  of  the  fungus,  (a)  being  a  check  or  uninoculated 
tube.  On  the  other  hand,  similar  plugs  taken  from  the  sweet 
potato,  apple,  and  cucumber  gave  practically  no  growths. 

2.  Sterilized  corn  meal  properly  mixed  with  water  was  the 
best  medium  used.  The  chief  difficulty  lies  in  inoculating 
these  tubes,  as  the  top  of  the  corn  meal  usually  dries  out  in  a 
short  time  into  a  hard  mass  and  this  may  prevent  the  fungus 
getting  a  proper  start.  On  the  other  hand,  the  mechanical  con- 
ditions allow  the  fungus,  when  once  started,  to  gradually  work 
down  toward  the  more  moist  base  of  the  tube.  To  facilitate 
inoculations  and  removal  of  tufts  of  the  fungus,  it  is  best  to 
have  the  corn  meal  in  a  slant  at  its  upper  end.  Plate  XXV,  b, 
shows  a  growth  of  the  mildew  on  corn  meal,  of  the  same  age  as 
those  shown  on  the  potato  plugs.  In  the  few  trials  made,  a  mix- 
ture of  ground  green  Lima  bean  pods  and  seeds  with  corn  meal 
gave  very  satisfactory  growths  and  probably  this  medium  with- 
out the  corn  meal  would  do  as  well.  Sterilized  potato  plugs, 
however,  gave  scarcely  any  growth,  and  according  to  Matruchot 


320        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

and  Molliard  this  is  due  to  the  mechanical  interference  of  the 
swollen  starch  grains  in  preventing  the  spread  of  the  fungus. 

3.  Agar  agar  cultures,  with  various  ingredients  added,  were 
tried,  but  on  the  whole  were  less  satisfactory  than  the  preced- 
ing media.  Most  of  these  cultures  gave  slight  growths,  while, 
in  all,  the  fungus  was  slow  in  developing.  Usually  a  slight 
growth  of  the  mycelium  penetrated  the  medium  and  a  more  or 
less  conspicuous  development  of  conidiophores  and  mycelium 
was  formed  on  the  surface.  Potato  and  pumpkin  juice  agar 
media  were  as  satisfactory  as  any  tried.  Plate  XXV,  c,  shows 
an  old  culture  on  pumpkin  juice  agaf,  in  which  the  development 
was  more  prominent  than  usually  obtained  on  agar  media. 

4.  Sterilized  manure,  earth,  mixtures  of  these  and  of  these 
with  other  ingredients  were  used  to  a  limited  extent  to  see  if 
they  would  furnish  proper  media  for  the  development  of  the 
fungus.  It  was  thought  that  if  this  was  the  case  there  might 
be  some  ground  for  believing  that  the  fungus  made  some  such 
development  in  nature.  In  all  of  these  trials  the  growths  made 
were  very  slight  or  there  was  none  at  all.  The  very  poor 
growths  noticed  were  due,  in  some  cases,  to  the  medium  added 
with  the  fungus  on  inoculation.  So  far  as  could  be  learned 
from  these  cultures  there  is  no  reason  for  believing  that  the 
fungus  makes  any  unknown  growth  in  the  soil. 

Results.  These  investigations  showed  that  the  fungus  can  be 
grown  in  artificial  cultures  rather  readily  under  favorable  con- 
ditions. The  cultures  can  be  kept  alive  for  some  time,  especially 
on  a  medium,  as  corn  meal,  allowing  the  fungus  to  spread 
slowly  through  it.  By  occasional  re-inoculations  the  fungus, 
apparently,  can  be  kept  indefinitely  in  culture.  In  some  cultures 
and  under  some  conditions,  there  is  a  more  luxuriant  develop- 
ment of  the  fungus  than  in  others.  The  most  conspicuous 
growths  usually  indicate  a  more  vigorous  mycelial  than  conidial 
development.  No  sign  of  an  oogonial  or  other  unknown  stage 
appeared  in  any  of  the  cultures.  In  one  case,  however,  there 
was  a  very  slight  growth  from  the  pieces  of  an  infected  tuber 
inserted  in  agar  tubes  and  in  this  medium  some  peculiar  swollen' 
bodies  were  formed  whose  nature  was  not  definitely  determined. 
They  resembled  somewhat  the  immature  so-called  oospores  that 
Smorawski  (7)  has  figured.  A  few  cross  inoculations  were 
tried  with  cultures  obtained  from  different  sources,  but  nothing 


DOWNY    MILDEW    OF   POTATOES.  321 

unusual  occurred.  These  trials  were  made  with  the  hope  that 
different  mycelial  strains  might  be  discovered  whose  growth 
together  would  result  in  the  production  of  oospores.  As  the 
different  cultures  were  few  in  number  and  were  obtained  chiefly 
from  the  same  vicinity,  but  during  two  different  years,  it  is  not 
desirable  to  draw  even  a  negative  conclusion  from  the  results. 

Perpetuation  of  the  Fungus. 

The  known  vegetative  and  reproductive  states  of  downy  mil- 
dews in  general  are  mycelium,  conidial  spores,  zoospores  and 
oospores.  The  conidial  spores  and  zoospores  are  so  short  lived 
that  these  fungi,  so  far  as  known,  have  to  depend  on  the  myce- 
lium and  oospores  to  carry  them  over  the  unfavorable 
winter  period.  In  the  following  paragraphs  is  discussed  how 
the  potato  blight  is,  or  possibly  may  be,  perpetuated. 

Dormant  mycelium  in  tubers.  So  far,  this  is  the  only  way 
in  which  it  is  positively  known  that  the  fungus  survives  the 
winter.  The  disease  caused  by  its  presence  in  the  tuber  does 
not  need  to  be  conspicuous,  and  in  fact  the  more  diseased  the 
tuber  the  less  capable  this  is  of  germinating  and  so,  presumably, 
the  less  likely  it  will  be  of  perpetuating  the  mildew.  The  fungus 
may  be  present  in  the  tuber  and  yet  escape  notice,  as  the  rot  is 
sometimes  very  superficial  and  slight ;  in  fact  DeBary  records 
a  case  where  the  fungus  grew  out  on  the  cut  surface  of  a  tuber 
he  was  using  for  an  experiment  on  the  supposition  that  it  was 
entirely  free  from  the  fungus.  This  being  true,  it  is  doubtful 
if  much  good  would  result  where  tubers  were  selected  to  avoid 
diseased  ones,  though  it  is  not  advisable,  of  course,  to  use  those 
showing  a  superficial  or  even  deep-seated  reddish  brown  dry 
rot.  The  mycelium  in  the  tubers  seems  to  be  much  less  active 
in  the  spring  than  when  the  tubers  are  first  dug.  Ordinarily 
in  the  fall  if  the  cut  surface  of  a  diseased  tuber  is  exposed  in  a 
damp  chamber  the  fungus  will  spread  more  or  less  over  this 
surface.  On  the  other  hand,  of  the  thirty  samples  obtained 
from  Connecticut  growers  and  tested  in  this  way  in  the  spring, 
the  fungus  developed  on  only  two  lots,  yet  most  of  those  tried 
had  the  appearance  of  blight  tubers.  This  decreased  activity  or 
vigor  of  the  fungus  is  apparently  due  to  the  drying  out  of  the 
tissues  of  the  tuber,  which  induces  a  hibernating  condition  of 

21 


322        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

the  mycelium,  and  in  some  instances  where  the  tubers  have  been 
stored  in  unusually  dry  places  no  doubt  the  mycelium  does  not 
survive. 

Two  views  are  advanced  to  explain  how  the  mycelium  in  the 
infected  tubers  planted  in  the  spring  perpetuates  the  fungus. 
First;  by  growing  up  from  the  tuber  into  the  stem,  it  produces 
a  "diseased  plant."  This  view  has  been  previously  discussed 
in  the  paper.  We  believe  that  the  mycelium  rarely  passes  up 
into  the  plants  in  this  way,  and  just  as  rarely  passes  down  from 
the  plants  after  infection  into  the  new  tubers,  as  was  formerly 
believed  by  some  investigators.  Second,  the  mycelium  forms 
the  conidial  stage  on  the  cut  surface  of  the  tubers  or  rarely  in 
tufts  through  punctures  in  the  skin,  and  the  conidial  spores  or 
their  zoospores,  on  being  carried  to  the  buds  of  the  tuber  or 
later  to  older  parts,  cause  infection.  The  chief  objection  to  this 
view  is  that  infection  in  this  way  probably  could  only  take  place 
during  a  short  time  in  the  spring  (the  writer's  and  DeBary's 
experience  indicates  that  the  mycelium  forms  the  conidial  spores 
only  on  the  living  and  not  on  the  badly  diseased  tissue  of  the 
tubers)  whereas  the  first  visible  outbreaks,  so  far  as  known, 
do  not  appear  until  July  or  August.  Could  it  be  possible  that 
owing  to  the  rapid  growth  of  the  young  plants  these  primary 
infections  remain  isolated  in  the  tissues  and  do  not  develop 
further  until  the  growth  of  the  host  ceases  and  faf orable  blight 
weather  appears  ? 

Hetercecism.  This  means  that  a  fungus  has  different  stages 
of  its  development  on  different  hosts,  as  is  the  case  of  the  wheat 
rust  with  two  stages  on  barberry  plants  and  later  two  more  on 
wheat.  DeBary,  who  first  demonstrated  this  life  cycle  of  the 
wheat  rust,  has  discussed  the  possibility  of  the  potato  mildew 
being  heteroecious.  He  concluded  that  there  was  no  likelihood 
of  this  being  so,  though  at  one  time  false  rumors  stated  he  had 
found  a  different  stage  on  another  host.  There  are  absolutely 
no  data  in  favor  of  such  a  supposition  for  the  potato  mildew 
and  no  evidence  of  heteroecism  has  ever  been  found  for  any 
of  the  downy  mildews. 

Unknozvn  stages.  Various  writers,  often  to  support  some 
theory,  have  suggested  possible  or  probabl^e  stages  of  the  potato 
mildew,  not  known  for  other  downy  mildews,  but  no  real  evi- 
dence of  their  existence  has  yet  been  produced.     For  instance, 


DOWNY    MILDEW    OF    POTATOES.  323 

Smith  (6,  p.  292)  writes :  "It  is  not  unreasonable  to  imagine 
that  some  other  condition  of  the  parasite,  at  present  quite 
unknown  to  and  unsuspected  by  us,  might  be  brought  to  Hght. 
The  fungus  may  exist  in  inconceivably  fine  dust-like  particles 
or  in  the  condition  of  a  mucous  fluid."  This  was  an  entirely 
theoretical  suggestion,  but  a  Scotchman,  A.  S.  Wilson  (8), 
advocated  a  more  definite  unknown  stage.  His  theory  was  as 
follows :  'Certain  bodies  were  found  on  the  under  side  of 
leaves,  in  all  parts  of  the  stem,  especially  at  the  nodes,  and  in 
the  tubers,  especially  around  the  eyes.  These  he  originally 
called  sclerotiets  (analogous  to  sclerotia)  but  later  named 
them  granules  of  mucoplasm.  They  are  translucent,  micro- 
scopic globular  bodies  coated  with  oxalate  of  lime.  His  obser- 
vations caused  him  to  believe  that  these,  on  germination,  gave 
rise  to  the  mycelium  of  the  potato  mildew  and  that  thus  the 
disease  could  break  out  on  any  part  of  the  host  without  trans- 
location. As  the  resting  spores  are  not  parasitic  but  live  and 
germinate  in  the  soil  or  in  any  dead  matter,  it  is  contact  with 
the  mucoplasm  exuded  from  their  fresh  mycelium  which 
originates  the  parasitism  in  the  potato.  As  the  tubers  are 
infected,  especially  at  the  eyes,  with  mucoplasm  granules,  the 
general  elements  of  the  parasite  are  carried  over  from  one  race 
of  potatoes  to  the  following  and  from  one  season  and  country 
to  another,  not  requiring  invasion  from  without  for  a  new  dis- 
play of  the  disease.'  This  is  apparently  a  case  where  there  is 
too  much  theory  and  too  little  exact  observation  and  no  experi- 
mentation to  back  it. 

Oospores.  These  are  thick- walled  sexual  spores  often  pro- 
duced by  the  downy  mildews  and  constitute  the  common  means 
by  which  they  are  carried  over  from  one  season  to  another. 
Several  investigators  claim  to  have  found  these  spores  for  the 
downy  mildew  of  potato,  but  in  no  case  have  they  produced 
sufficient  evidence  to  satisfy  botanists  in  general  of  their  reality. 
Different  suggestions  have  been  advanced  to  account  for  the 
absence  or  rarity  of  these  spores,  and  these,  briefly  summarized, 
are  as  follows:  i.  That  the  oospores  have  never  existed  for  the 
potato  mildew.  2.  That  this  mildew  has  lost  the  power  to  pro- 
duce these  bodies.  3.  That  they  may  occur  only  in  certain 
regions  of  the  world.  4.  That  they  are  produced  only  in  cer- 
tain hosts, — the  potato  mildew  having  been  found  on  a  number 


324        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

of  Other  plants.  5.  That  they  are  formed  in  the  potato  more 
as  a  saprophyte  than  as  a  parasite.  6.  That  possibly  these 
spores  are  formed  only  on  the  union  of  distinct  mycelial  strains 
which  do  not  commonly  occur  together — a  suggestion  by  the 
author. 

The  more  the  writer  looks  into  this  matter  the  more  he  is 
inclined  to  believe  that  oospores  of  the  potato  mildew  do  exist, 
especially  since  he  has  recently  demonstrated  their  presence  for 
the  closely  related  species  occurring  on  the  Lima  bean.  There- 
fore, so  far  as  he  is  concerned,  the  first  two  suggestions  given 
above  may  be  dismissed  as  unsatisfactory.  Those  persons  who 
suggest  special  regions  where  the  oospores  may  be  found  name 
Chili,  the  original  home  of  the  potato,  as  a  possible  locality  or 
region  where  the  genus  Solanum  occurs  in  a  wild  state.  This 
mildew  has  been  recorded  on  a  number  of  the  Solanaceae,  more 
especially  on  the  genus  Solanum,  and  even  on  a  couple  of  the 
Scrophulariaceae  family.  The  writer  has  not  had  opportunity 
to  study  the  blight  to  any  extent  outside  of  Connecticut,  and, 
besides  the  potato,  has  collected  it  only  on  the  tomato.  Spec- 
imens of  the  latter,  collected  both  in  Connecticut  and  Porto 
Rico,  did  not  throw  any  light  on  the  oospores.  The  question 
of  hosts  and  distribution  cannot,  therefore,  be  discussed  on  the 
basis  of  personal  experience.  The  fifth  and  sixth  suggestions, 
however,  have  had  our  attention  during  the  past  two  years  and 
may  be  discussed  further. 

Are  oospores  produced  in  decaying  potato  tissues?  Worth- 
ington  Smith,  of  England,  was  the  most  prominent  advocate 
of  the  existence  of  oospores  and  claimed  to  have  found  them 
commonly  in  that  country  in  the  decaying  leaves  and  tubers. 
The  Royal  Horticultural  Society  awarded  him  a  gold  medal 
for  his  alleged  discovery.  While  his  investigations  were  made 
twenty  to  thirty  years  ago,  they  have  never  been  substantiated 
unquestionably.  At  the  same  time  he  was  at  work,  DeBary, 
of  Germany,  the  most  able  mycologist  of  his  time,  was  also 
undertaking  a  study  of  the  potato  disease  at  the  request  of  the 
Royal  Agricultural  Society  of  England.  He  was  unable  to  find 
any  positive  evidence  of  oospores  and  he  criticized  Smith's  work 
severely  and  apparently  on  good  grounds.  There  is  no  doubt 
that  Smith  did  not  always  record  accurate  observations,  and 
there  is  little  doubt  that  in  his  study  of  the  developing  "oospores" 


DOWNY    MILDEW    OF   POTATOES.  32$ 

he  dealt  with  more  than  one  fungus.  The  chief  question  is, 
however,  did  he  have  under  consideration  at  any  time  true 
oospores  of  this  fungus.  Unfortunately  the  writer  can  not 
give  a  positive  opinion  on  this  question,  as  he  has  not  seen 
Smith's  specimens  and  has  so  far  been  unable  to  confirm  his 
results.  The  drawings  he  gives  of  the  mature  spores  in  his 
book  (6)  resemble  such  spores,  but  other  of  his  drawings  are 
questionable.  But  even  DeBary  (2)  does  not  deny  that  some 
of  the  bodies  Smith  described  might  have  been  oospores,  for  he 
says,  "The  warty  bodies  are  possibly  its  oospores."  In  another 
place  in  this  same  article  DeBary  also  says:  "Ever  since  the 
oospores  of  a  Peronospora  were  discovered,  innumerable 
searches  have  been  made  for  those  of  Phytophthora.  I  have 
myself  looked  for  them  in  the  stalks,  leaves,  flowers,  fruit  and 
tubers  of  the  potato.  In  July  of  the  present  year  (1875),  when 
the  fungus  appeared  in  this  district  in  sad  abundance,  I  obtained 
a  very  large  amount  of  material  for  study  and  at  the  same  time 
secured  the  kindly  assistance  of  two  botanists  experienced  in 
researches  of  this  kind,  Dr.  Rostafinski  and  Dr.  Stahl.  But 
again  only  negative  results  were  arrived  at."  Since  Smith's 
time,  Smorawski  and  others  have  claimed  to  have  found  the 
oospores,  but  these  claims  always  lack  positive  proof.  How- 
ever, most  botanists  probably  believe  with  DeBary  that  they 
will  be  found  sometime.  He  said,  "That  they  will  be  regularly 
found  somewhere  or  other  is  assumed,  for  our  knowledge  of  the 
habits  of  numerous  allied  fungi  make  this  more  than  probable." 
Smith  stated  that  it  was  an  easy  matter  to  obtain  the  oospores 
by  merely  placing  a  number  of  diseased  leaves  overlapping  each 
other  in  a  moist  chamber  and  examining  them  as  they  rotted 
down.  The  writer  has  tried  his  method  a  number  of  times  but 
never  succeeded  in  finding  spores  that  were  decidedly  suspicious. 
True,  one  frequently  finds  various  kinds  of  rounded,  usually 
isolated,  bodies  in  such  leaves,  some  of  which  are  apparently 
spores  of  fungi  and  others  merely  encysted  stages  of  the  lower 
animals.  Even  if  one  were  to  find  the  oospores  under  these 
conditions,  it  would  be  a  difficult  matter  to  accurately  trace  their 
development  because  of  probable  confusion  at  times  with  other 
things.  After  considerable  search  in  the  dying  and  dead  leaves 
and  stems,  it  finally  seemed  to  the  writer  that  the  diseased 
tubers  offered  the  most  likely  place  for  the  formation  of  the 


326        CONNECTICUT    EXPERIMENT    STATION    REPORT,    IQCS- 

oospores.  Consequently  these  have  been  searched  in  all  stages 
of  infection  and  decay  and  at  various  times  of  the  year.  While 
some  suspicious  bodies  have  been  seen  from  time  to  time,  no 
very  definite  evidence  has  been  gained  that  the  fungus  produces 
oospores  even  here.  If  they  are  formed  in  the  tubers  it  is  only 
in  the  decayed  parts,  as  the  healthy  tissue  offers  little  opportu- 
nity for  their  development  and  no  suspicious  signs  have  been 
found  there.  Examination  of  tubers  decayed  from  a  dry 
reddish  brown  rot  usually  shows  the  presence  of  the  peculiar 
short  haustoria  of  the  blight  fungus  and  these  seem  to  become 
more  prominent  and  develop  thick,  swollen  walls  with  the 
advance  of  the  decay.  Often  two  of  these  haustoria  are  seen 
standing  side  by  side  in  a  cell,  and  while  they  indicate  a  living 
mycelium,  even  in  advanced  stages  oi  rot  and  disintegration 
of  the  tuber,  nothing  definite  concerning  any  further  develop- 
ment of  them  or  the  mycelium  has  been  made  out.  Resting 
spores  with  thick  walls  and  somewhat  of  the  type  of  oospores 
have  been  seen,  but  there  was  never  any  evidence  that  they 
were  formed  from  the  mycelium  of  the  blight  fungus.  The 
potato  tuber  before  its  final  dissolution  in  the  ground  is  the 
workshop  of  many  different  fungi,  as  well  as  of  the  lower 
animals,  hence  the  necessity  of  caution  in  forming  decided 
opinions  of  forms  found  there.  These  tubers  finally,  through 
the  work  of  the  animal  life,  are  more  or  less  scattered  through 
the  .soil,  so  that  if  oospores  are  formed  they  would  secure  more 
or  less  of  a  local  distribution  in  the  soil,  probably  about  the 
time  the  blight  appears  in  the  fields. 

Mycelial  strains.  In  recent  papers  Blakeslee*  has  shown  that 
in  a  related  family,  Mucoraceae,  certain  species  possess  mycelial 
strains,  apparently  of  a  sexual  nature,  that  produce  zygospores 
only  when  these  grow  together.  Securing  artificial  cultures 
of  the  two  strains,  which  he  calls  -|-  and  — ,  of  such  a  species,  he 
was  able  to  produce  the  zygospores  at  will  merely  by  inocula- 
ting the  same  cultural  tube  with  both  forms.  In  the  study  of 
various  downy  mildews  it  has  occurred  to  the  writer  that  possi- 
bly similar  conditions  are  true  for  certain  of  these  fungi,  and  in 
our  Report  for  1904  this  was  suggested  as  a  possibility  for  the 


*  Science,  19:  864-6.     1904.     Proc.  Amer.  Acad.  Arts  Sci.,  40:   203-321. 
1904. 


DOWNY    MILDEW    OF   POTATOES.  32/ 

potato  mildew.  Some  effort,  as  stated  previously,  has  been 
made  to  secure  such  strains  in  pure  cultures  and  prove  the 
theory  by  cross  inoculations,  but  as  yet  no  evidence  has  been 
secured  in  this  way.  While  no  positive  proof  has  been  gained 
for  this  belief,  there  are  yet  certain  facts,  as  given  in  the  next 
paragraph,  that  may  be  considered  at  least  favorable  to  it. 

In  the  first  place  the  oospores  of  the  Peronosporeae,  like  the 
zygospores  of  the  Mucoraceae,  are  not  commonly  found  in  nature. 
There  are  species,  other  than  the  potato  mildew,  for  which  they 
have  never  been  found ;  others  for  which  they  have  been  rarely 
found;  some  for  which  they  have  been  found  only  on  certain 
of  their  hosts ;  and  finally,  some  in  which  they  are  not  uncom- 
mon if  looked  for  at  the  proper  time  and  place.  All  of  these 
facts  are  in  favor,  rather  than  against,  distinct  mycelial  strains 
(heterothallic  forms)  except  the  last,  which  might  indicate  a 
homothallic  form  (one  which  contains  both  antheridia  and 
oogonia  on  the  same  mycelium).  Secondly,  our  culture  experi- 
ments with  the  Lima  bean  and  potato  mildews,  both  species 
of  Phytophthora,  is  in  accord  with  this  theory.  The  potato 
mildew  cultures  never  produced  oospores  under  any  con- 
dition, possibly  because  there  was  but  one  strain  present,  and 
our  cultures  of  the  Lima  bean  mildew  ran  to  the  production  of 
oospores,  possibly  because  the  cultures  were  obtained  from 
material  containing  both  strains.  The  potato  mildew  cultures 
often  gave  a  very  evident  aerial  growth  of  the  mycelium  and 
conidiophores,  while  this  development  in  cultures  of  the  Lima 
bean  mildew  was  usually  inconspicuous,  though  in  nature  its 
conidial  stage  is  much  more  prominent  than  that  of  the  potato 
mildew.  Thirdly,  Smith,  in  a  drawing  of  the  development  of 
his  supposed  oospores  of  the  potato  mildew,  shows  two  different 
mycelia.  side  by  side,  one  producing  oogonia  and  the  other 
antheridia.  DeBary  at  first  criticized  this  on  the  ground  that 
the  oogonia  and  antheridia  were  not  on  threads  in  anatomical 
relation  with  each  other,  but  later,  according  to  Smith,  withdrew 
this  criticism.  Smith,  of  course,  may  have  shown  in  this  draw- 
ing something  having  no  connection  with  the  potato  mildew, 
yet  in  all  of  the  drawings,  seen  by  the  writer,  of  DeBary  (i) 
and  others  showing  the  development  of  oogonia  of  various  mil- 
dews, the  antheridia  and  oogonia  are  always  figured  on  threads 
having  no  connection  with  each  other.     It  is  true  that  only  a 


328        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I905. 

short  piece  of  each  thread  is  shown  in  these  drawings,  but  it 
is  usually  difficult  to  trace  these  further.  In  our  study  of  the 
Lima  bean  mildew  effort  was  made  to  follow  these  threads  as 
far  as  possible,  and  the  evidence,  so  far  as  obtained,  pointed 
to  their  independent  origin,  so  that  they  could  easily  have  been 
borne  on  two  different  mycelia  closely  interwoven. 

Delayed  appearance  of  blight.  It  is  not  as  yet  definitely 
known  why  the  blight  does  not  appear  earlier  in  the  potato 
fields.  The  weather  in  May  and  sometimes  in  early  June  is  as 
favorable  for  its  development  as  that  of  July  and  August,  when 
it  does  first  appear.  On  the  face  this  would  indicate  that  the 
germs  for  infection  were  not  generally  available  so  early  in  the 
year,  and  yet  this  is  the  very  time  when  the  mycelium*  in  the 
seed  tubers  underground  is  best  situated  for  producing  the 
conidial  stage  on  them.  DeBary  possibly  explains  this  delayed 
appearance  in  the  following  statement:  "From  large  exper- 
ience I  consider  it  probable  that  Phytophthora  grows  more 
easily  on  a  plant  at  the  height  of  its  development  than  on  young 
stalks  and  leaves.  It  would  be  interesting,  but  not  easy,  to 
establish  this  clearly  by  experiment."  In  the  writer's  experi- 
ments already  given  it  was  found  possible  to  easily  infect  young 
leaves  and  stems,  but  whether  the  subsequent  development  of 
the  fungus  was  more  or  less  vigorous  than  on  old  tissues  was 
not  a  point  at  issue.  Possibly  the  point  previously  suggested 
in  this  article  explains  the  late  appearance;  viz.,  that  the 
mycelium  from  primary  infections  on  young,  rapidly  growing 
tissue  remains  localized  until  after  vegetative  growth  of  the 
host  ceases  and  then  renews  its  activity  on  the  appearance  of 
favorable  blight  weather.  If  the  primary  infections,  however, 
usually  take  place,  as  the  writer  believes,  by  contact  of  the 
leaves  with  the  ground,  this  is  best  accomplished  in  the  full 
growni  plants.  The  young  plants  are  rigid  and  shoot  straight 
up  out  of  the  ground,  and  by  the  time  they  have  attained  any 


*  According  to  DeBary's  and  our  experience  the  mycelium  will  produce 
its  conidial  stage  only  in  the  living  tissues  of  the  tubers,  but  Massee,  on 
the  other  hand,  reports  this  stage  in  the  old  diseased  tubers  even  a  year 
after  they  have  rotted ;  if  the  fruiting  stage  found  by  him  was  developed 
by  the  germination  of  oospores,  this  apparent  conflict  of  observations 
might  be  explained. 


DOWNY    MILDEW    OF    POTATOES.  329 

considerable  growth  and  are  likely  to  lop  over  on  the  ground, 
the  wet  weather  of  the  spring  is  largely  past.  If  it  were  known 
definitely  that  oospores  were  produced,  the  most  feasible  expla- 
nation would  be  that  these  did  not  germinate  until  the  wet 
weather  of  July  and  August  and  then  their  zoospores  in  the 
moist  earth  infected  the  leaves  that  were  washed  down  in  con- 
tact with  them  by  the  rains.  This  would  agree  perfectly  with 
what  the  writer  has  been  able  to  ascertain  so  far,  of  the  primary 
infections  in  the  fields. 

Literature. 

The  botanical  and  general  agricultural  literature  dealing  with 
the  potato  mildew  is  perhaps  more  extensive  than  that  for  any 
other  fungus.  There  are  given  here  merely  a  few  articles,  to 
which  reference  has  been  made  in  the  preceding  discussions. 

1.  DeBary,  A.     Recherches  sur  le  developpement  de  Quelques  Champig- 

nons   Parasites.     Ann.    Sci.    Nat.    Bot.    IV,    20:     5-148.      1863. 
[Illustr.] 

Deals  in  this  paper  especially  with  the  Peronosporeae  and  gives 
considerable  information,  with  illustrations,  of  the  potato  mildew. 

2.  DeBary,    A.      Researches    into    the    Nature    of    the    Potato    Fungus, 

Phytophthora  infestans.    Journ.  Bot.,  n.  s.,  5:    105-26,  149-54.    1876. 
[Illustr.] 

Gives  in  this  excellent  paper  the  life  history  of  the  fungus,  so 
far  as  known,  and  treats  especially  of  his  studies  made  for  the 
Roy.  Agr.  Soc.  of  England  and  a  criticism  of  Worthington  Smith's 
so-called  oospores. 

3.  Massee,  G.    Diseases   of   the   Potato.    Journ.   Roy.   Hort.    Soc,   29: 

139-41-     1904. 

Gives  short  general  account  of  the  mildew  and  makes  two  rec- 
ommendations, based  on  field  and  laboratory  observations,  for 
keeping  it  in  check;  namely,  collection  of  the  diseased  and  old  seed 
tubers  at  harvest  time  and  use  of  seed  tubers  showing  no  sign  of 
disease. 

4.  Matruchot,  L.  and  Molliard,  M.    Sur  la  culture  pure  du  Phytoph- 

thora infestans  DeBary,  agent  de  la  maladie  de  la  pomme  de  terre. 
Bull.  Soc.  Myc.  Fr.,  16:   209-10.     1900. 

Note  that  they  have  been  able  to  grow  this  fungus  on  living 
and  sterilized  media  in  pure  and  artificial  cultures. 

5.  Matruchot,  L.  and  Molliard,  M.      Sur    le    Phytophthora    infestans. 

Ann.  Myc,  i:  540-3.     1903. 

Give  further  more  extended  notes  on  the  artificial  cultures  of 
this  fungus  on  living  and  sterilized  slices  of  potato  and  pumpkin; 


330        CONNECTICUT   EXPERIMENT    STATION    REPORT,    I905. 

note  that  the  fungus  does  not  discolor  the  living  plugs  of  potato 
if  grown  pure ;   found  no  oospores. 

6.  Smith,  W.  G.     Potato  Disease,  I,  II.  ,  Diseases  of  Field  and  Garden 
f  Crops :    275-329.     1884.     [lUustr.] 

Makes  an  extended  report  on  Phytophthora  infestans  in  both  its 
active  and  passive  state;  discusses  in  detail  his  discovery  of 
oospores. 

7.  Smorawski,  J.     Zur  Entwicklungsgeschichte  der  Phytophthora  infes- 

tans   (Montagne)    DeBy.     Landwirthsch.   Jahrb.,   19:    1-12.     i8go. 
[Illustr.] 

Gives  a  general  account  of  the  investigations  of  others  and 
records  observations  and  experiments  of  his  own;  describes  and 
illustrates  immature  oospores  that  he  connects  with  this  fungus. 

8.  Wilson,  A.  S.     Potato    Disease   and    Parasitism.     Trans.    Proc.    Bot. 

Soc.  Edinburgh,  19:   656.     1891. 

Explains  his  mucoplasm  theory,  by  which  he  accounts  for  the 
spread  of  the  blight. 


PLATE    XIII. 


Apple. 


a.     Fruit  Speck,  p.  264. 


Lima  Bean. 


b.     Leaf  Blight,  p.  265. 


FUNGI   OF  APPLE  AND  LIMA  BEAN. 


PLATE    XIV. 


Catalpa. 


a.     Leaf  Spot,  p.  266. 
Celeriac. 


b.     Leaf  Spot,  p.  267. 
FUNGI   OF   CATALPA  AND   CELERIAC. 


a.     Leaf  Scorch,  a  physiological  trouble,  p.  267. 


Nectarine. 


b.     Scab,  p.  268. 


DISEASES  OF   MAPLE  AND   NECTARINE. 


PLATE    XVI. 


■**'>!**'     " 


a.     Showing  upward  progress  of  disease  by  cliaracter  of  leaves. 
Diseased.  Healthy. 


b.     Longitudinal  and  cross  sections  of  stems,  showing  how  tissues  are  injured. 
WILT  OF  OKRA,  p.  268. 


PLATE   XVII. 


a.     Onion  Brittle,  showing  peculiar  malformation  of  leaves,  p. 270. 


b.     Bacterial  Black  Spot  of  Plum,  p.  273. 


DISEASES  OF   ONION   AND  JAPANESE    PLUM. 


PLATE   XVIII. 


Spinach. 


^'  'M'--  # 


wn 

m 

I^^R 

Wi 

W^/ 

^ 

^-»^! 

^A|^^ 

**■."• 

-in 

> 

t 

'^- 

^"ggtfg 

*%iivft??S?t"'  iT^^M^^ 

r 

b.     Powdery  Mildew,  p.  276. 
FUNGI   OF   SPINACH   AND   STRAWBERRY. 


PLATE   XIX. 


a.     Cultures  of  the  fungus  on  potato  agar,  showing  sclerotia. 


b.     Showing  how  the  fungus  injures  base  of  stems. 
DAMPENING  OFF  FUNGUS  OF  YOUNG  TOBACCO  PLANTS,  p.  276. 


PLATE   XX. 


a,  mycelium;  b,  antheridium;  c,  oogonium;  d,  oosphere;  e,  oospore.  Figs. 
1-7,  showing  character  of  myceHum.  Figs.  8-21,  antheridia  and  oogonia  and 
their  development.  Figs.  22-25,  mature  oogonia  and  oospores.  Magnified 
about  600  diameters. 


DEVELOPMENT  OF   MYCELIUM  AND  OOSPORES  OF   LIMA  BEAN   MILDEW, 
Phytop]itlio)-a  J'/iaseoli . 


PLATE   XXI. 


•  •t 


a.     Diseased  seed  containing  oospores,  except  healthy  one  at  **,  pp.  292,  297. 


b.     Showing  injury  to  young  stems  and  leaf,  p.  281. 


DOWNY  MILDEW  OF  LIMA  BEAN,  Phytophtlwya  Phascoli. 


PLATE    XXII. 


a.     Showing-  mildew  in  young  and  old  state  on  pods. 


b.     Showing  portion  of  infected  pod  enlarged  two  diameters. 


DOWNY  MILDEW  OF   LIMA  BEAN,  Pbyfophthora  P/iascoli,  p.  280. 


PLATE   XXIII. 


h^ 


a.     Showing  primary  infection  from  contact  witli  ground,  p.  309. 


b.     Artificial  infection  of  the  mildew  on  cut  surface  of  tuber,  p.  318. 


DOWNY  MILDEW  OR  BLIGHT  OF   POTATO,  Phytophtlwra  infcstaus. 


PLATE    XXIV. 


a.    Two  lower  and  tip  of  third  leaf  killed  by  fungus,  lo  days  after  inoculation,  p.  315. 


b.     Central  diseased  shoot  grown  from  an  inoculated  tuber,  p.  307. 
INFECTION  EXPERIMENTS  WITH  Phytophtlwra  infestans. 


PLATE    XXV. 


a.     On  plugs  of  living  potato,     a,  check. 


b.     On  corn  meal. 


c.     On  pumpkin  agar. 


ARTIFICIAL  CULTURES  OF  Phytoplithora  iufcstans,  p.  317- 


Agrictaltiara^ 
CoUegre 


State  of  Connecticut 


REPORT 

OF 


The  Connecticut  Agricultural 
Experiment  Station 

FOR  THE  YEAR   I9O6 

PART  V. 
REPORT  OF  THE  STATION  BOTANIST 


CONNECTICUT 

AGRICULTURAL   EXPERIMENT 
STATION 


REPORT   OF  THE   BOTANIST, 

G.  P»  CLINTON,  ScD, 


I.   Notes  on  Fungous  Diseases,  etc.,  for  1906,  p.  307. 
II.  Experiments  to  prevent  Onion  Brittle,  p.  332. 

III.  Dry  Rot  Fungus,  Mertilius  lacry7nans  (Wulf.)  Schum.,  p.  336. 

IV.  Root  Rot  of  Tobacco,  Thielavia  basicola  (B.  &  Br.)  Zopf,  p.  342. 


ISSUED  MAY,  1907 


PART  V. 

REPORT  OF  THE  BOTANIST  FOR  1906. 

G.  P.  Clinton,  Sc.D. 


I.     NOTES  ON  FUNGOUS  DISEASES,  ETC.,  FOR  1906. 

GENERAL    NOTES   ON    DISEASES    PREVIOUSLY   REPORTED. 

During  the  year  1906  fungous  diseases  as  a  rule  were  not 
especially  troublesome  in  Connecticut.  In  this  respect  it  was 
like  the  preceding  year,  though  the  distribution  of  the  moisture 
was  somewhat  different.  In  1905  the  drier  part  of  the  growing 
season  came  before  August,  and  the  moister  period  was  during 
August  and  September;  but  in  1906  the  moist  weather  came 
in  June  and  July,  while  the  latter  part  of  the  season  was 
dry.  During  last  June  there  was  a  rainfall  of  5.14  inches, 
which  was  over  two  inches  in  excess  of  the  average  rainfall  of 
the  past  34  years;  July  also  gave  a  slight  excess  over  the 
average.  This  abundance  of  moisture  was  favorable  for  start- 
ing certain  fungous  troubles,  but  as  it  came  in  thunder  showers, 
without  especially  cloudy  or  foggy  weather,  and  as  August  and 
September  were  largely  free  from  rains,  the  fungous  troubles 
on  the  whole  did  not  become  prominent.  A  peculiarity  of  the 
season,  however,  was  the  large  number  of  leaf  scorch  or  similar 
troubles,  due  to  peculiar  weather  conditions  dliring  June  and 
July. 

The  diseases  mentioned  in  the  following  paragraphs  are  old 
troubles  that  were  unusually  serious  or  that  were  less  injurious 
than  usual.  They  are,  grouped  according  to  their  hosts,  as 
follows : 

Apple.  Sooty  blotch,  Phyllachora  pomigena,  was  very  prom- 
inent the  past  fall  on  apples  all  over  the  state.  This  is  now  one 
of  the  most  serious  fungous  troubles  of  the  apple  in  Connect- 
icut.   While  the  fungus  was  especially  conspicuous  in  the  small 


3o8        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

orchards,  and  on  the  few  trees  kept  by  each  farmer  for  home 
use,  it  also  did  more  injury  than  usual  in  the  larger  orchards, 
even  when  they  had  been  sprayed.  One  could  scarcely  find  any 
good  specimens  of  Greenings,  in  the  fall  and  early  winter 
markets,  because  of  blemishes  by  this  superficial  parasite. 
Black  rot  or  canker,  Sphaeropsis  Malorum,  was  also  frequently 
sent  to  the  Experiment  Station  for  identification. 

Asparagus.  A  single  grower  in  Norwalk  reported  one  of 
his  beds  seriously  injured  by  the  rust,  Puccina  Asparagi,  but 
the  writer  did  not  have  opportunity  for  determining  whether 
or  not  this  trouble  was  common. 

Beans.  The  downy  mildew  of  the  Lima  beans,  Phytophthora 
Phaseoli,  did  some  injury,  but  was  probably  not  quite  so  injur- 
ious as  the  previous  year.  A  grower  in  Southport,  however, 
reported  a  crop  practically  destroyed  by  it.  The  oospores  of 
this  fungus  were  again  found,  thus  indicating  that  they  are 
probably  not  so  uncommon  as  supposed.  Anthracnose  of 
string  beans,  Colletotrichum  Lindemiithianum,  was  more  com- 
mon and  injurious  than  for  several  years. 

Cucumber  and  muskmelon.  On  the  whole  these  plants  suf- 
fered less  than  usual  from  fungous  attacks.  The  growers  even 
had  a  fair  crop  of  muskmelons.  More  or  less  injury,  however, 
was  done  by  the  downy  mildew,  Peronoplasmopara  Cubensis, 
and  the  leaf  mold,  Altentaria  Brassicae  var.  nigrescens. 

Grape.  The  black  rot,  Guignardia  Bidwellii,  and  possibly 
other  rots,  were  considerably  more  injurious  than  usual.  Spray- 
ing failed  to  satisfactorily  control  this  trouble  in  some  cases. 

Onion.  There  was  considerable  complaint  of  poor  onions  in 
1906.  Most  of  the  trouble  was  due  to  the  character  of  the 
season  and  insects.  Fungi  were  responsible  to  a  less  degree 
in  some  cases.  There  seems  to  be  a  tendency  of  onions  grown 
for  seed  in  the  onion  districts  of  the  state  to  deteriorate.  The 
cause  of  this  decline,  however,  is  not  yet  satisfactorily  deter- 
mined, though  in  some  seasons  fungous  troubles  seem  to  be 
largely  responsible.  Onion  brittle  was  more  conspicuous  this 
year  than  last,  in  the  infected  fields  in  the  neighborhood  of 
Guilford,  since  it  seems  to  be  a  soil  trouble  that  increases  in 
extent  each  year.  A  discussion  of  this  disease,  including  experi- 
ments made  to  control  it,  is  given  elsewhere  in  this  report. 


NOTES   ON    FUNGOUS   DISEASES   FOR    I906.  309 

Peach.  While  last  year  there  was  considerable  injury  from 
the  brown  rot,  Sclerotinia  friictigena,  this  year  the  peaches  were 
almost  entirely  exempt  from  it.  Some  little  rot  appeared  at 
first  on  the  early  varieties  that  are  most  subject  to  decay,  but 
the  weather  as  a  whole  was  so  fair  and  dry  during  the  picking 
season  that  the  crop  was  conspicuous  for  its  fair  size,  good 
quality  and  freedom  from  rot. 

Pear  and  qviince.  There  were  a  few  complaints  of  the  bac- 
terial blight,  Bacillus  amylovorus,  on  pear,  and  one  grower 
informed  the  writer  that  he  had  never  seen  this  trouble  so 
injurious  to  his  quince  trees  as  it  was  this  year. 

Potato.  Tip  burn  and  early  blight,  Alternaria  Solani,  were 
more  common  than  usual.  The  wet  weather  of  June  and  July 
came  at  a  time  most  favorable  for  the  development  of  the  early 
blight,  while  the  sudden  alternation  of  bright,  hot  days  with 
those  of  abundant  rainfall  was  responsible  for  most  of  the  tip 
burn,  rather  than  any  long  period  of  dry  weather.  There  were 
some  unusual  cases  of  injury  to  potato  leaves  in  June  that  were 
hard  to  account  for  except  on  this  basis.  The  late  blight, 
Phytophthora  infestans,  because  of  the  wet  weather  of  June 
and  July  appeared  this  year  considerably  earlier  than  the  pre- 
vious year,  the  first  specimens  being  found  on  July  23rd,  as 
compared  with  August  nth,  in  1905.  However,  the  dry 
weather  of  August  and  September  prevented  the  fungus  from 
causing  even  the  ordinary  damage.  There  was  a  little  injury 
to  the  foliage  of  the  early  potatoes,  where  the  vines  grew  rankly, 
and  a  little  rot  shov?ed  in  their  tubers;  but  the  injury  was  soon 
checked  by  the  dry  weather.  Although  we  had  unusual  oppor- 
tunity for  learning  of  injury  in  late  potatoes,  there  was  abso- 
lutely no  complaint  of  rot  anywhere  in  the  state.  Without 
question  the  late  blight  did  the  least  damage  in  the  state  this 
season  of  any  of  the  five  years  the  writer  has  had  it  under 
observation. 

Raspberry.  The  wilt  of  raspberry,  Leptosphaeria  Coniothy- 
rium,  which  has  been  complained  of  in  a  general  way  for  some 
years  past,  was  unusually  prominent  during  June  and  July  of 
the  past  season,  since  complaints  were  received  from  a  number 
of  places  scattered!  over  the  state  of  the  wilting  of  the  half 
matured  fruit.     Further  mention  of  this  trouble  is  made  under 


3IO        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

new  diseases  because  of  a  new  discovery,  concerning  its  inocu- 
lation by  insects,  which  was  brought  out  in  our  study  of  the 
trouble.  Aside  from  the  wilt,  this  was  a  very  good  year  for 
raspberries. 

Tobacco.  The  early  spring  seems  to  have  been  rather 
unfavorable  for  tobacco  seed  beds,  since  dampening  off  and  root 
rot  troubles  were  more  conspicuous  than  usual.  The' weather 
for  curing  tobacco  in  the  barns  at  the  end  of  the  season,  how- 
ever, was  so  unusually  favorable  that  pole  burn  did  no  damage 
whatever,  and  the  tobacco  cured  much  earlier  than  usual. 

NEW    DISEASES. 

Each  year  a  certain  number  of  fungi  occurring  on  economic 
plants  are  observed  that  have  not  been  reported  previously  in 
this  state,  or  old  species  are  found  on  new  hosts,  or  some  new 
point  is  made  out  in  the  life  history  of  a  fungus.  Such  data 
are  recorded  in  the  following  paragraphs.  Some  of  the  fungi 
briefly  mentioned,  though  of  little  economic  importance  at 
present,  may  eventually  become  conspicuous  enough  for  more 
extended  notice  later.  By  recording  from  time  to  time  these 
new  observations,  we  aim  to  have  finally  a  complete  survey  of 
all  the  diseases  of  cultivated  plants  of  the  state.  Most  of  the 
troubles  reported  this  year  are  entirely  new,  special  note  being 
made  of  the  exceptions.  As  usual,  we  distinguish  between 
those  diseases  caused  by  fungi  and  bacteria,  and  physiological 
troubles  caused  by  unfavorable  environment  (such  as  heat, 
moisture,  wind,  cold,  etc.).  The  common  names  of  the  latter 
class  are  printed  in  italics,  while  those  of  the  former  are 
printed  in  small  caps,  followed  by  the  scientific  name  of  the 
fungus. 

APPLE,  Pints  Mains. 

Winter  Injury  and  Canker,  Sphaeropsis  Malorum  Pk.  Plat6 
XVII,  a.  We  have  reported  before  injuries  due  to  the  severe 
cold  of  winter,  and  those  caused  by  the  canker  fungus,  but  last 
spring  Dr.  Britton  called  to  our  attention  a  peculiar  trouble  of 
apple  limbs  that  seemed  to  be  due  to  a  combination  of  these 
causes.  The  specimens  were  from  an  apple  grower  of  West 
Hartford,  who  first  noticed  the  trouble  while  pruning  his  trees. 
The  specimens  sent  to  the  Station  for  examination  showed  large 


NOTES    ON    FUNGOUS   DISEASES    FOR    I906.  3II 

dead  sunken  areas  in  the  bark,  usually  starting  from  dead  twigs, 
and  apparently  caused  by  the  canker  fungus,  since  it  was  in 
fruiting  condition  on  some  of  the  specimens.  Some  of  the 
smaller  of  the  injuries  had  been  outgrown  by  the  development 
of  a  new  growth  of  bark  beneath.  Another  and  more  peculiar 
feature  of  the  trouble  was  the  enlargement  of  the  limbs  into 
somewhat  fusiform  swellings,  as  shown  in  the  illustration.  In 
some  cases  several  of  the  swellings  followed  one  another  on 
the  same  limb.  These  enlargements  generally  showed  a  greater 
swelling  on  one  side  than  on  the  opposite,  and  often  the  bark 
was  split  down  the  more  swollen  side.  Cross  and  longitudinal 
sections  showed  that  the  swellings  were  apparently  the  result 
of  severe  cold,  which  had  injured  the  limbs  unevenly  along  the 
branch,  as  shown  by  the  blackened  wood  on  the  injured  portion. 
The  winter  injury  was  most  severe  on  the  side  of  the  limb  least 
swollen,  and  had  restricted  the  growth  of  the  woody  layers  the 
following  years,  while  on  the  swollen  side  the  wood  had  made  a 
greater  growth,  as  shown  by  the  larger  annual  rings.  The 
growth  of  the  bark  had  been  affected,  too,  by  the  winter  injury, 
but  was  thickest  on  these  swellings,  and  as  a  rule  had  made  a 
greater  growth  on  the  injured  side.  The  longitudinal  cracks 
in  the  bark  apparently  had  not  been  caused  by  winter  injury, 
but  by  the  abnormal  and  excessive  growth  of  the  wood  on  the 
more  swollen  side  of  the  branch.  The  cracks  only  extended 
through  the  outer  bark,  as  a  healthy  growth  of  new  bark  beneath 
was  healing  them  over.  Here,  then,  we  have  a  case  of  winter 
injury  to  limbs  acting  irregularly  (possibly  due  to  unequal 
maturity  of  wood  at  the  time  of  the  injury)  so  that  as  a  whole 
it  stimulated  the  bark  to  unusual  activity  at  the  injured  places, 
the  wood  on  one  side  of  the  limb  being  so  injured  as  to  retard 
growth  the  following  years,  while  on  the  other  side  the  injury 
was  so  slight  as  really  to  act  as  a  stimulus  to  unusual  growth. 
The  cankered  areas  occurred  on  the  sides  most  injured,  and 
apparently  the  canker  fungus  largely  got  a  start  here  through 
the  smaller  twigs  that  had  been  entirely  winter  killed. 

BEANS,  Phaseohis  vulgaris. 

Leaf  Scorch.  During  the  early  summer  Mr.  Andrew  Ure  of 
Hamden  called  the  writer's  attention  to  a  field  of  string  beans 
that  had  been  injured  suddenly  by  some  cause  that  rendered 


312        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

many  of  the  plants  worthless.  The  injury  resembled  somewhat 
the  bacterial  blight  of  this  host,  but  an  examination  of  the 
injured  tissues  'failed  to  reveal  bacteria  or  any  fungus  as  the 
probable  cause.  The  leaves  in  some  cases  were  entirely  dead, 
but  in  others  only  a  part  of  the  leaves  were  injured.  The  irreg- 
ular area  of  dead  tissue  of  the  leaves  partially  injured  was 
usually  separated  from  the  healthy  by  a  reddish  purple  border, 
but  there  was  no  water-soaked  appearance,  as  is  usually  the 
case  with  the  bacterial  trouble.  Examination  failed  to  reveal 
any  more  probable  cause  than  leaf  scorch,  due  to  bright,  warm 
weather  suddenly  following  a  very  violent  rain  storm,  with  high 
winds,  which  occurred  shortly  before  the  trouble  was  first 
noticed.  A  peculiar  feature,  however,  was  that  some  other 
bean  fields  in  the  neighborhood  did  not  suffer  from  this  trouble. 
This,  while  difficult  to  explain,  might  have  been  due  to  the 
variety  of  beans,  their  age,  or  unknown  differences  in  the  soil 
conditions. 

CARNATION",  Dianthus  Caryophyllus. 

Spot^  Alternaria  sp.  This  disease  was  called  to  the  writer's 
attention  by  Mr.  Walden  of  this  Station,  who  collected  speci- 
mens in  the  greenhouse  of  Mr.  S,  Perry  Beers  of  Greenfield 
Hill.  Mr.  Beers  had  obtained  his  carnations  already  rooted 
from  another  greenhouse,  where  this  trouble  was  also  present. 
In  a  few  cases  the  disease  was  severe  enough  to  kill  the  plants 
outright,  but  usually  the  injury  was  limited  to  the  leaves 
dying  at  their  tips  or  to  the  whole  top  of  the  plant  dying  as  the 
result  of  a  girdled  area  beneath.  Generally  the  injured  places 
were  of  a  whitish  color  having  a  rather  inconspicuous  black 
growth  of  the  fruiting  stage  of  the  fungus.  The  only  mention 
of  .a  similar  disease  of  carnation  caused  by  Alternaria  that  the 
writer  has  seen  is  that  made  by  Mr.  Orton  in  the  Yearbook  of 
the  U.  S.  Department  of  Agriculture  for  1905  (p.  611).  Mr. 
Woods,  of  the  Department  of  Agriculture,  who  has  made  a 
special  study  of  the  fungus,  in  a  recent  letter  to  the  writer 
says : — 

"The  disease  is  quite  serious  on  the  softer-leaved  varieties,  such  as 
those  of  the  Lawson  type,  especially  the  Lawson  and  the  Enchantress. 
The  disease  behaves  very  much  like  the  other  Alternaria  diseases, 
especially  the  one  on  the  violet,  attacking  not  only  the  leaves,  but  the 


NOTES   ON    FUNGOUS   DISEASES    FOR    I906.  313 

Stems,  and  cutting  the  plants  back  very  seriously  in  many  cases.  In 
fact,  I  have  seen  w^hole  houses  of  carnations  practically  stripped  of 
their  leaves  and  losing  a  large  part  of  the  top.  Plants  grov^rn  out  of 
doors,  exposed  to  rain  and  dew,  especially  in  the  night,  are  very  subject 
to  the  disease  and  suffer  seriously  when  the  plants  are  moved  into 
the  house.  It  is,  of  course,  then  rather  difficult  to  free  the  plants 
of  the  disease  without  cutting  them  back  very  severely  and  spraying 
them  thoroughly  with  soap  Bordeaux.  The  proper  treatment  is  to 
spray  the  plants  from  the  time  they  are  set  in  the  field  until  the  time 
they  are  moved  into  the  house,  keeping  the  young  growth  well  covered 
with  Bordeaux  and  continuing  the  treatment  after  the  plants  are  in 
the  house  until  they  become  well  established.  If  the  plants  are  grown 
in  the  house  all  of  the  year  and  the  leaves  are  not  allowed  to  remain 
wet  over  night,  the  disease  seldom,  if  ever,  does  much  injury." 

CAULIFLOWER,  Brassica  oleracea. 

Black  Rot_,  Pseudomonas  campestris  (Pammel)  Smith. 
While  the  black  or  brown  rot  of  cabbage,  turnips  and  allied 
plants  is  not  a  rare  bacterial  trouble,  it  has  never  been  definitely 
reported  in  this  state.  From  occasional  complaints  received 
from  growers,  there  is  little  doubt  that,  while  not  reported 
before,  it  has  been  present  for  some  time,  doing  more  or  less 
injury.  Last  October  the  writer  made  his  first  collection  of 
this  disease  from  some  cauliflowers  grown  on  the  Experiment 
Station  grounds.  The  heads  were  blackened  and  blasted,  much 
as  if  injured  by  frost.  There  was  also  complaint  of  a  rot 
of  turnips  on  a  Hamden  farm  which  no  doubt  was  also  of  this 
nature,  though  no  specimens  were  seen.  The  black  rot  bacteria 
usually  enter  their  hosts  through  injured  tissue  or  the  water 
pores  at  the  margin  of  the  leaves.  The  bacteria  develop  abun- 
dantly in  the  fibro-vascular  vessels,  working  from  the  veinlets 
into  the  large  veins  and  ribs,  which  are  turned  black  as  a  result 
of  the  invasion.  Finally  they  may  reach  the  stem,  and  cause 
a  more  general  injury.  As  a  result  of  the  clogging  and  disease 
of  the  bundles,  the  water  supply  is  gradually  cut  off  from  the 
fleshy  tissue,  and  the  leaves  turn  yellow,  wilt,  and  finally  die. 
In  diseased  cabbage,  the  bacteria  sometimes  work  their  way 
directly  from  the  infected  leaf  through  adjacent  leaves,  causing 
an  internal  rotting  while  the  head  from  the  outside  may  appear 
sound.  When  this  disease  appears  in  a  field,  rotation  with  non- 
cruciferous  crops  should  follow  for  a  few  years.    The  diseased 


314        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

plants  should  be  destroyed,  and  rubbish  from  the  plants  should 
never  get  into  the  manure  pile.  It  has  lately  been  shown  that 
the  bacteria  causino-  this  disease  can  be  carried  on  the  seed  and 
cause  infection  of  the  young  plants,  so  care  should  be,  used  to 
obtain  seed  from  healthy  plants. 

CORN,  Zea  Mays. 

Black  Mold,  Cladosporium  Zeae  Pk.  This  is  a  fungus  that 
sometimes  appears  conspicuous  on  both  sweet  and  field  corn, 
though  it  is  not  strictly  a  parasite,  and  possibly  not  directly 
the  cause  of  any  injury.  It  shows  as  an  olive-black  growth  on 
the  kernels,  usually  at  the  tip  of  the  ears.  Apparently  it  devel- 
ops on  improperly  matured  or  injured  kernels,  and  makes  this 
injury  appear  more  conspicuous.  When  the  seed  corn  is  not 
properly  dried  before  storage  or  is  left  too  long  stacked  in 
damp  places,  the  fungus  probably  extends  the  injury.  While 
Peck  described  this  fungus  as  a  distinct  species,  it  is  quite  pos- 
sible that  it  is  not  distinct  from  th"e  common  saprophytic  black 
mold,  Cladosporium  herbarium  (Pers.)  Lk.  The  renewed 
interest  taken  by  some  of  our  growers  in  the  selection  of  seed 
corn  is  likely  to  call  their  attention  to  the  fungus  as  one  of  the 
blemishes  of  perfect  seed  ears,  especially  of  the  sweet  corn. 

GRAPE,  Vitis  sps. 

Bitter  Rot^  Glomerella  rufomaculans  (Berk.)  Spald  &  von 
Schr.  This  fungus  has  previously  been  found  in  this  state  on 
the  apple  and  pear,  but  not  until  the  past  season  on  the  grape. 
On  the  apple  it  certainly  does  not  do  the  damage  here  that  it 
does  further  south,  and  possibly  its  injury  to  the  grape  is  also 
inconspicuous.  Just  how  common  the  grape  bitter  rot  is  in 
the  state,  however,  cannot  be  stated  at  present,  as  usually  all 
the  rots  of  grapes  are  indiscriminately  called  the  black  rot. 
This  season  it  was  found  in  one  place  at  Westville,  where  it 
seemed  to  be  the  cause  of  considerable  decay,  and  a  few  berries, 
chiefly  rotting  from  other  causes,  were  also  found  among  speci- 
mens sent  from  New  Haven  and  New  London.  The  spores 
ooze  out  in  small  pinkish  masses,  and  by  these  the  rot  can  often 
be  told  with  the  naked  eye  from  the  more  common  black  rot. 


NOTES    OX    FUNGOUS    DISEASES    FOR    I906.  315 

Blue  Mold^  Penicilliiim  glaucum  Lk.  A  trouble  which  has 
not  been  reported  before,  but  which  is  common,  is  that  caused 
by  the  ordinary  blue  mold  found  on  cold  storage  grapes, 
especially  towards  the  end  of  their  season.  The  fungus  attacks 
the  grapes  that  are  more  or  less  bruised  by  packing  or  handling ; 
also  where  the  grapes  are  overripe  it  seems  to  gain  entrance 
at  their  stem  end.  Along  the  cracks  in  the  skin  the  fruiting 
stage  of  the  mold  shows  at  first  as  a  whitish,  but  soon  as  a 
dusty,  blue-green  growth.  Of  course  all  such  berries  are  worth- 
less, and  the  spores  from  these  form  the  means  for  a  much 
more  general  spread  of  the  trouble  through  the  basket.  While 
usually  but  few  grapes  are  injured,  if  sold  soon  after  removal 
from  cold  storage,  after  they  are  out  some  time  the  trouble 
may  even  spoil  the  whole  basket.  Some  of  the  baskets  offered 
for  sale  last  fall  had  as  high  as  a  third  of  the  grapes  spoiled  in 
this  way.  Another  quite  similar  blue  mold,  (Aspergillus 
glaucus)  may  also  at  times  be  partly  responsible  for  this  decay, 
as  one  of  the  cqltures  made  from  the  grapes  showed  that  it  was 
present. 

Shelling  and  Rot.  One  case  of  serious  shelling  off  of 
Niagara  grapes,  about  the  time  of  maturity,  was  reported  from 
New  London,  and  the  same  variety  at  the  Experiment  Station 
was  similarly  injured.  As  in  both  of  these  cases  the  grapes 
rotted  more  or  less,  especially  after  falling  to  the  ground,  it  is 
a  question  whether  or  not  some  fungus  might  have  been  par- 
tially responsible  for  the  trouble.  It  is  generally  conceded, 
however,  that  shelling  (without  rot)  is  the  result  of  non-para- 
sitic causes.  Among  the  non-parasitic  causes  the  peculiar  sea- 
sonal conditions  of  the  year,  already  mentioned  elsewhere,  which 
apparently  caused  an  unusual  number  of  physiological  troubles, 
may  have  been  the  chief  cause  of  this  trouble.  The  grapes  on 
the  ground  in  time  showed  the  fruiting  stage  of  a  species  of 
Macrophoma.  This  fungus  probably  occurred  on  them  as  a 
saprophyte ;  at  least  Macrophoma  flaccida  (on  the  fruit)  and 
Macrophoma  rimiseda  (on  the  branches),  which  agree  some- 
what closely  with  the  species  reported  here,  are  usually  con- 
sidered non-parasitic  species.  The  shelling  of  Niagara  grapes 
has  been  mentioned  once  before,  by  Sturgis,  in  the  Experiment 
Station  Report  for  1896,  p.  278.    Since,  through  oversight,  this 


3l6         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

was  not  included  among  the  troubles  mentioned  by  the  writer 
in  his  general  report  of  diseases,  made  in  1903,  and  since  it  was 
probably  a  common  trouble  the  past  season,  the  following  is 
quoted  from  Sturgis'  article: — 

"Shelling  grapes,  at  least  in  the  case  of  green  varieties,  show  a 
peculiar  though  indistinct  mottling  of  the  surface;  the  skin  is  abnor- 
mally thick,  and  the  whole  berry,  therefore,  feels  harder  than  healthy 
berries  at  the  same  stage  of  development;  a  section  of  a  diseased 
berry  shows  a  narrow  brown  zone  just  beneath  the  skin;  the  taste  of 
shelling  grapes  is  noticeably  insipid  as  compared  with  the  tart,  astrin- 
gent flavor  of  the  unripe  but  healthy  fruit;  finally,  the  woody  tissues 
of  the  stem  which  enter  the  fruit  and,  in  the  case  of  sound  berries, 
remain  attached  to  the  stem  when  the  berry  is  pulled  off,  are  so  far 
weakened  in  the  case  of  shelling  grapes  that  the  weight  of  the  berry 
is  sufficient  to  cause  them  to  separate  from  the  stem,  and  the  berries 
fall  to  the  ground,  leaving  the  ends  of  the  stem  perfectly  even,  'as  if  cut 
with  a  knife.'  This  dropping  of  the  fruit  from  two  to  three  weeks 
before  maturing,  is  a  characteristic  symptom  of  shelling,  and  may  result 
in  very  serious  loss,  a  loss  emphasized  by  the  fact  that  the  trouble  does 
not  confine  itself  to  certain  bunches  on  a  vine,  leaving  others  unaffected, 
but  affects  portions,  generally  the  end,  of  every  bunch. 

After  a  most  exhaustive  consideration  of  all  the  possible  causes  of 
shelling,  Lodeman  concludes  that  neither  insects  nor  fungi  are  to  be 
considered  as  a  primary  cause  of  the  trouble;  that  the  condition  of 
the  soil,  apart  from  the  supply  of  available  plant  food,  does  not  exercise 
any  marked  influence  on  the  degree  of  shelling;  that  meteorological 
conditions  are  not  primarily  responsible  for  it ;  and  that  it  is  not  due 
to  a  lack  of  phosphoric  acid.  Among  the  agencies  which  may  increase 
or  favor  the  diseased  condition,  Lodeman  mentions  parasitic  fungi, 
which  weaken  the  function  of  the  leaves ;  a  weakening  of  the  plant  due 
to  overbearing;  the  drawing  of  nourishment  from  the  fruit  by  over- 
production of  wood;  an  excessive  supply  of  nitrogen,  emphasized  by 
too  much  tillage;  long  drought  or  excessive  rains  following  drought; 
and  a  poorly  developed  root  system,  resulting  in  a  general  weakening 
of  the  plant.  The  condition  of  the  food  supply  as  regards  potash 
seems  to  be  the  only  remaining  factor  to  be  considered,  and  Lodeman 
is  inclined  to  attribute  the  primary  cause  of  shelling  to  a  lack  of  that 
element.  This  view  is  in  a  measure  substantiated  by  observation  and 
experiment." 

OATS,  Avena  sativa. 

Yellow  Leaf.  This  trouble  was  first  seen  at  Portland,  the 
second  week  in  June.  During  June  and  July  it  was  noticed  in 
almost  all  the  oat  fields  examined,  and  so  must  have  consider- 
ably reduced  the  yield.    The  leaves,  especially  the  lower,  became 


NOTES    ON    FUNGOUS   DISEASES   FOR    I906.  317 

a  sickly  yellow,  and  many  finally  died  prematurely.  In  some 
respects  this  trouble  resembled  the  bacterial  disease  that  occa- 
sionally occurs  in  the  early  summer  in  the  oat  fields  of  the 
West;  but  the  leaves  lacked  the  water-soaked  appearance  of 
that  disease,  and  on  examination  failed  to  show  any  bacteria 
present.  The  trouble  apparently  resulted  from  unfavorable 
weather  conditions,  possibly  aggravated  by  some  root  disease, 
though  the  few  examinations  made  of  the  roots  failed  to  show 
any  suspicious  fungus  at  work  there.  June  and  July  had  many 
heavy  rain  storms  suddenly  followed  by  bright  hot  days,  and 
these  sudden  changes,  as  in  other  cases  already  mentioned, 
probably  caused  the  injury.  The  same  trouble  was  seen  to  a 
less  degree  on  a  number  of  other  grasses,  both  wild  and 
cultivated. 

PEACH,  Prunus  Persica. 

Leaf  Fall.  Another  physiological  trouble  called  to  the 
writer's  attention  by  J.  H.  Hale,  of  Glastonbury,  at  the  annual 
meeting  of  the  Connecticut  Pomological  Society,  was  the 
unusual  loss  of  the  peach  foHage  in  his  orchard  during  August 
and  September.  Many  of  the  leaves  turned  yellow,  finally 
dying  and  dropping  off.  In  some  cases  there  was  some  shot- 
hole  injury,  but  otherwise  nothing  to  indicate  that  any  fungus  or 
insect  was  the  cause  of  the  defoliation.  Conversation  with  a 
number  of  other  large  peach  growers  brought  out  the  fact  that 
this  defoliation  was  a  common  trouble  this  year  in  the  state. 
Both  bearing  and  young  trees  were  affected,  but  certain  vari- 
eties more  than  others.  Alberta  and  Late  Crawford  were 
among  the  varieties  that  suffered  most.  Some  of  the  growers 
were  inclined  to  believe  that  fungi  or  insects  were  the  cause 
of  the  trouble.  From  their  descriptions,  however,  it  seems  that 
neither  of  these  agents,  if  responsible,  was  at  work  on  the 
leaves  themselves.  The  San  Jose  scale,  if  very  bad  on  a  tree, 
may  cause  partial  defoliation,  but  there  was  no  likelihood  that 
it  was  unusually  prominent  in  the  orchards  complained  of.  It 
is  barely  possible  that  such  denudation  of  the  trees  might  fol- 
low root  injury.  There  is  no  fungus  trouble  in  the  state,  how- 
ever, that  has  been  known  to  act  exactly  in  this  way.  The 
crown  gall  and  the  crown  or  foot  rot  are  the  only  root  troubles 
so  far  known  here,  and' it  does  not  seem  plausible  that  either 


3l8        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

of  these  was  responsible  for  so  general  and  unusual  a  trouble. 
Among  the  insects  the  peach  borer  is  the  only  one  that  might 
be  suspected,  but  if  this  was  responsible,  it  would  undoubtedly 
have  been  detected  by  the  growers,  and  its  injury  is  not  quite 
like  that  described  here.  Everything  considered,  it  seems  prob- 
able that  this  was  also  one  of  the  seasonal  physiological  troubles 
that  were  unusually  common  this  year.  The  wet  months  of 
June  and  July  no  doubt  developed  a  tender  and  luxuriant  leaf 
growth  on  the  trees,  and  the  bright,  dry  months  of  August  and 
September  offered  such  different  conditions  (especially  if  the 
roots  still  showed  any  effects  of  winter  injury  from  the  cold 
winter  of  1903-04)  that  the  evaporation  of  moisture  from  the 
leaves  became  disproportionate  to  the  amount  supplied  by  the 
roots,  and  the  defoliation  of  the  older  leaves  gradually  followed 
as  a  consequence. 

PEONY,  Paeonia  sp. 

Root  Injury  or  Rot?  Plate  XVII,  b.  In  September  com- 
plaint was  received  from  Southington  of  a  root  rot  of  peonies, 
which  had  gradually  become  quite  serious.  In  writing  of  this 
trouble,  the  grower,  Mr.  H.  R.  Whitney,  said:  "When  the 
plants  first  became  established  they  were  very  beautiful,  but 
since  this  disease  has  come  upon  them  they  do  not  amount  to 
anything,  some  not  even  blooming.  The  first  sign  noticed  is  a 
discoloration  of  the  leaves,  turning  to  a  chocolate  color,  accom- 
panied by  wilting,  and  finally  death  of  the  stalk.  Sometimes 
the  wilting  occurs  without  any  discoloration ;  the  roots  seem  to 
rot  to  pieces  at  the  surface  of  the  ground  much  after  the  man- 
ner of  the  rootstock  rot  of  iris  (which,  by  the  way,  is  very 
prevalent  hereabouts,  and  all  our  iris  beds  are  seriously  affected 
by  it).  These  peonies  were  set  on  a  sloping  hillside  facing  the 
north,  and  the  lowest  plants  were  the  first  ones  affected.  The 
disease  has  now  spread  to  all.  They  have  always  had  good 
care.  I  am  now  going  to  transplant  them  to  higher  ground,  in 
fresh  soil,  and  see  what  this  will  do." 

I  am  not  certain  about  the  cause  of  this  trouble.  The  speci- 
mens sent  for  examination  showed  a  dry,  rather  than  a  wet 
rot,  though  possibly  this  was  because  they  had  dried  out  some- 
what.    The  statement  that  the  iris  on'  his  grounds  was  being 


NOTES   ON    FUNGOUS   DISEASES   FOR    I906.  319 

injured  by  a  bacterial  rot  might  indicate  that  the  same  agent 
was  at  work  on  the  peony.  An  examination  of  the  roots,  how- 
ever, did  not  lead  the  writer  to  the  conclusion  that  bacteria 
were  responsible  for  the  injury,  though  some  bacteria  were 
present  in  the  tissues,  and  cultures  made  from  the  diseased 
parts  usually  gave  mixed  growths  of  bacteria  and  fungi. 
Microscopic  examination  of  the  diseased  tissues  showed  that 
there  was  present  the  sterile  mycelium  of  some  fungus  that 
looked  as  if  it  might  be  the  cause  of  the  trouble.  The  fungus 
was  peculiar  because  of  numerous  roundish,  dark  reddish 
brown  chlamydospore-like  bodies  that  occurred  in  the  threads. 
Cultures  from  this  tissue  seem  to  indicate  that  these  were 
possibly  threads  of  a  Torula  developing  under  unfavorable  con- 
ditions. In  this  case  the  fungus  was  apparently  only  a  sapro- 
phyte that  developed  in  the  tissue  after  the  injury,  rather  than 
its  cause.  A  peculiarity  of  the  trouble,  at  least  in  the  specimens 
sent  for  examination,  was  the  sharpness  with  which  the  healthy 
tissue  was  marked  off  from  the  diseased,  as  shown  by  the 
lengthwise  section  of  the  root  in  the  illustration  given  here. 
This  may  indicate  that  the  trouble  was  not  the  result  of  bac- 
terial or  fungous  attack,  but  possibly  a  winter  injury.  Usually 
the  injury  was  on  one  side  of  the  root,  but  in  some  cases  it 
extended  up  into  the  interior,  with  white  healthy  tissue  on  either 
side.  Mention  of  this  trouble  has  not  been  found  in  the  liter- 
ature of  plant  diseases,  though  probably  it  has  not  entirely 
escaped  observation  before.  Further  study  of  injured  plants 
is  needed  to  determine  definitely  the  cause. 

PINE,  Pinus  sps. 

Leaf  Blight^  Hypod'erma  Desmazierii  Duby.  This  caused 
the  pine  needles  to  die  from  the  tip  inward,  changing  the  normal 
green  color  to  a  reddish  brown,  and  in  time  to  a  grey  brown. 
On  the  lighter  areas  the  spore  stage  of  the  sac  fungus  which 
causes  the  injury  developed  as  small,  longitudinal  black  lines. 
The  fungus  does  more  or  less  injury  to  the  large  pitch  pine 
trees,  Pinus  rigida,  in  this  state,  but  just  how  much  is  not 
known.  Undoubtedly  it  causes  in  time  a  premature  defoliation 
of  the  infested  leaves.  No  complaint  has  been  made  in  this 
country  of  the  fungus,  though  in  Europe  Tubeuf  &  Smith  men- 


3  20        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

tion   a   similar   species   on   white   pine   as    doing  considerable 
injury. 

RusT^  Peridermiuni  acicolum  Und.  &  Earle.  During  the 
spring,  complaint  was  received  of  a  fungus  injuring  the  leaves 
of  the  pitch  pine  on  an  estate  at  South  Manchester.  '  As  the 
owner  wished  to  develop  the  young  native  trees  into  a  pitch 
pine  grove  for  landscape  effect,  she  was  anxious  that  no  seri- 
ous injury  be  done  by  this  fungus.  The  writer  made  a  special 
study  of  the  fungus,  with  the  result  that  some  new  features  of 
its  life  history  were  brought  to  light.  The  fungus  forms  on 
the  leaves  fragile,  tongue-shaped,  whitish  receptacles  filled  with 
orange-colored  spores.  By  the  first  of  July  these  had  largely 
disappeared,  as  the  fungus  did  not  spread  further  on  the  pine 
leaves.  It  was  found  that  this  stage  was  merely  the  aecial  stage 
of  another  rust  (Coleosporium  Solidaginis)  that  is  common  on 
goldenrods  and  asters.  In  July,  following  the  disappearance  of 
the  rust  on  the  pine  leaves,  this  other  rust  became  very  abundant 
on  the  leaves  of  Solidago  rugosa  in  this  forest,  especially  where 
these  plants  were  close  to  the  infected  pines.  The  writer  was 
also  able  to  produce  the  rust  on  an  indoor  specimen  of  Solidago 
rugosa  by  infecting  it  with  spores  taken  from  the  pine  leaves, 
thus  conclusively  proving  their  relationship.  The  rust  at  South 
Manchester  appeared  chiefly  on  the  young  trees  six  to  fifteen 
feet  high,  whose  limbs  in  many  cases  reached  the  ground. 
Some  few  large  trees  with  no  limbs  near  the  ground  were  not 
at  all  infected.  In  order  to  prevent  the  spread  of  the  trouble, 
at  the  suggestion  of  the  writer,  the  young  trees  were  trimmed 
of  their  lower  branches,  and  the  goldenrod,  especially  under  the 
trees,  was  all  cut  off.  In  this  way  it  was  hoped  to  prevent 
any  large  amount  of  reinfection  of  the  pine  leaves  from  the 
rust  on  the  goldenrod  another  season.  The  writer  hopes  to 
make  a  more  detailed  account  of  his  study  of  this  fungus 
elsewhere. 

Winter  Injury  f  The  state  forester,  Mr.  Hawes,  recently 
had  called  to  his  attention  a  trouble  of  white  pine,  Pinus 
Strohus,  at  Windsor.  The  injured  trees  were  scattered  through 
the  forest,  and  some  were  of  large  size,  so  that  their  death 
meant  considerable  financial  loss.  The  injury  first  showed  in 
the  death  of  the  leaves  on  the  uppermost  branches,  but  gradu- 


NOTES   ON    FUNGOUS   DISEASES   FOR    I906.  32 1 

ally  progressed  downward  until  the  whole  tree  was  dead.  An 
examination  of  the  injured  and  dead  trees  by  Mr.  Britton,  the 
entomologist,  showed  that  while  some  were  infested  with  a 
number  of  borers,  these  usually  confined  their  attention  to  the 
dead  or  dying  parts  of  the  trunk,  and  were  not  species  liable 
to  directly  cause  such  injury.  The  writer  saw  several  badly 
injured  trees  (but  still  possessed  of  a  living  trunk  and  some 
green  leaves)  which  had  blown  over,  and  an  examination  of 
these  showed  in  every  case  that  the  roots  were  all  dead  except 
a  few  small  and  apparently  new  ones  near  the  surface  of  the 
ground.  This  plainly  indicated  that  the  injury  was  primarily 
one  of  the  roots.  At  first  we  were  inclined  to  believe  that  the 
roots  had  been  winter  killed,  but  an  examination  showed  that 
the  mycelium  of  some  hymenomycetous  fungus  was  present  in 
the  dead  roots  and  to  some  extent  on  the  surface  of  the  living. 
This  fungus  was  not  determined,  as  its  fruiting  stage  was  not 
present  at  the  time  of  the  examination,  in  March.  Of  course 
it  is  possible  that  the  fungus  was  present  merely  as  a  saprophyte. 
A  similar  injury  in  Massachusetts  was  recently  called  to  the 
writer's  attention  by  Professor  Stone,  who  after  a  thorough 
study  has  attributed  it  to  winter  injury. 

EASPBERRY,  Rubiis  sps. 

WiLT_,  Leptosphaeria  Coniothyrium  (Fckl.)  Sacc.  Plate 
XVIII,  a.  This  trouble  has  been  mentioned  before  in  the 
Reports  for  1903  and  1904,  but  this  year  there  were  morecom- 
plaints  of  serious  injury  from  it  than  any  previous  year.  A 
more  thorough  study  of  the  trouble  has  developed  a  new  point 
in  its  life  history.  Apparently  the  very  wet  weather  of  June 
offered  favorable  conditions  for  the  development  of  the  fungus, 
as  it  began  to  be  quite  conspicuous  in  its  injury  in  the  fruit 
about  the  middle  of  the  month.  At  this  time  the  disease  showed 
on  a  few  of  the  young  canes,  which  gradually  wilted  from  the 
top  as  if  they  had  been  injured  below  in  cultivation.  Examina- 
tion of  these  showed  no  such  injury,  but  rather  a  rot  at  the  base 
or  under  the  ground  apparently  due  to  the  wilt  fungus,  though 
not  in  a  fruiting  condition  to  fully  identify  it.  Cankered  areas 
(as  described  by  Stewart,  of  the  Geneva,  N.  Y.,  Station,  who 
23 


322        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

has  made  a  special  study  of  this  trouble)  may  also  occur  on 
various  parts  of  the  plant,  and  by  girdling  produce  a  wilt  of 
the  parts  above.  On  the  fruiting  or  dead  canes  the  fungus 
usually  appears  more  generally  distributed  in  its  fruiting  con- 
dition. From  minute  imbedded  receptacles  in  the  bark  large 
numbers  of  the  spores  are  shed  out  on  the  surface  as  a  dark 
reddish  brown  coating.  On  the  pruned  canes  the  fungus  often 
gains  entrance  through  the  cut  ends,  killing  the  tips  and  pro- 
ducing its  fruiting  stage  on  the  dead  tissues.  The  most  serious 
injury  shows  on  the  green,  but  nearly  full-grown  berries, 
which  begin  to  wither  and  diy  up  about  the  middle  of  June. 
This  usually  occurs  so  prominently  and  suddenly  as  to  alarm 
the  grower,  who  has  not  previously  noticed  the  trouble,  as 
indicated  by  the  following  letter  from  Mr.  W.  B.  Eastman  of 
Bethel: — "This  a.  m.  I  noticed  that  many  of  the  berries 
throughout  the  entire  field  were  dying.  I  am  afraid  that  the 
entire  crop  will  be  lost  should  the  dying  continue." 

The  writer  had  previously  had  this  drying  up  of  the  berries 
called  to  his  attention,  and  had  attributed  it  to  the  fungus  at 
work  in  an  obscure  way  at  the  base  of  the  plants,  or  in  under- 
ground parts,  as  usually  there  was  no  evidence  of  it  on  these 
canes  above  ground.  These  plants  at  Mr.  Eastman's  were 
bearing  for  the  first  time  and  showed,  as  a  whole,  good  vigorous 
canes  except  for  the  wilting  of  the  fruit.  There  was  a 
little  of  the  wilt  fungus  present  on  old  stems,  and  a  few  new 
ones  were  dying  from  it,  but  in  general  there  did  not  seem  to 
be  any  special  reason  why  the  fruit  of  certain  canes  should  wilt 
and  in  other  cases  not.  This,  with  the  fact  that  the  wilting 
or  drying  up  of  the  berries  started  on  certain  ones  of  a  bunch 
before  it  did  on  others,  and  a  single  berry  might  be  dried  up  on 
one  side  while  perfectly  green  and  healthy  on  the  other  side, 
suggested  that  possibly  the  trouble  was  not  due  to  a  wilting 
caused  by  the  fungus  at  work  at  the  base  of  the  canes,  but  rather 
was  a  dry  rot  due  to  direct  infection  of  the  berries  by  this 
fungus.  This  same  idea  had  been  suggested  some  years  before 
to  the  writer  by  a  grower  whose  berries  had  been  thus  dried 
up,  but  our  imperfect  examination  at  that  time  showed  nothing 
Jo  support  the  belief.  This  time,  however,  it  was  proved  to  be 
correct    by    a    microscopic    examination    of    the    diseased    and 


XOTES    ON    FUNGOUS    DISEASES    FOR    I906.  323 

healthy  tissues.  In  the  healthy  green  tissues  no  sign  of  the 
mycelium  of  the  fungus  was  found,  but  in  the  adjacent  dis- 
eased tissues  it  was  present  more  or  less  prominently.  In  the 
berries,  for  instance,  it  formed  slightly  tinted  branched  threads 
that  worked  their  way  into  and  between  the  cells  of  the  fleshy 
parts  of  the  drupelets,  but  not  into  the  stony  tissue  or  the 
embryo.  When  first  infecting  the  berries,  the  fungus  caused 
the  normal  green  color  to  become  slightly  tinted,  as  if  ripening 
prematurely;  then  the  tissues  gradually'  turned  brown  and 
dried  up  from  the  dry  rot,  which  under  favorable  conditions 
of  moisture  advanced  through  the  whole  berry,  into  its  recep- 
tacle and  the  calyx,  and  finally  even  down  into  its  pedicel,  kill- 
ing the  tissues  as  it  advanced.  The  illustration  given  in  Plate 
XVIII,  a,  shows  the  upper  three  berries  perfectly  healthy  while 
those  in  the  low^er  row  are  entirely  rotted  by  the  fungus  except 
in  the  center  berry,  where  the  fungus  had  passed  down  the 
pedicel  only  halfway,  the  lower  half  being  still  alive  and  green, 
as  shown  by  the  lighter  color.  When  going  down  the  pedicels 
and  peduncle,  the  mycelium  penetrates  through  the  paren- 
chyma cells  of  the  bark,  kills  the  young  cambium  cells,  and 
is  also  found  in  the  cells  of  the  pith.  Just  how  far  down  the 
cells  of  the  stem  the  mycelium  may  pass  was  not  noted  by 
later  examination  of  the  canes.  Certainly  it  often  goes  far 
enough  to  wilt  other  berries  in  the  bunch  that  may  have 
escaped  direct  inoculation,  though  in  this  particular  case  most 
of  the  berries  seemed  to  have  been  inoculated  directly. 

While  the  fungus  was  not  found  in  fruiting  condition  on 
the  berries,  the  search  was  not  continued  later  than  June. 
Neither  did  specimens  brought  into  the  laboratory  and  kept  for 
a  short  time  in  a  moist  chamber  develop  the  fruiting  stage  on 
the  diseased  berries,  but  in  one  case  where  a  bunch  was  kept  in 
water  for  some  time,  the  fungus  did  finally  fruit  on  the  com- 
mon peduncle.  There  was  no  other  suspicious  fungus  in  Mr. 
Eastman's  patch,  and  while  this  one  was  not  so  common  in 
Its  fruiting  condition  as  seen  later  in  other  patches,  it  was  quite 
common  nearby  on  wild  plants  along  the  roadside,  whose  fruit 
was  sufifering  from  a  similar  dry  rot.  There  is  no  doubt  in  the 
writer's  mind  that  the  infection  took  place  through  the  flowers 
and  very  young  fruit,  and  that  the  spores  were  carried  bv  bees 


324         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

or  Other  insects  that  had  previously  crawled  over  stems  coated 
with  the  spores. 

This  wilt  seems  to  be  most  severe  on  the  blackcap  varieties. 
Among  those  complained  of  are  the  Parmer,  Cumberland  and 
Kansas.  To  a  less  extent  it  has  injured  the  red  varieties.  As 
stated  above,  it  was  also  found  on  wild  black  raspberries  and  a 
few  bundles  of  wild  blackberries  were  seen  that  possibly  may 
have  been  suffering  from  the  same  trouble.  When  once  the 
fungus  becomes  established  in  a  patch,  it  is  apt  to  give  trouble 
thereafter,  and  in  some  instances  it  has  eventually  ruined  the 
patch.  The  few  spraying  experiments  that  have  been  tried 
have  not  been  very  effective.  Possibly  if  the  spraying  was 
kept  up  for  two  or  three  years,  better  results  might  be  expected. 
It  is  quite  difficult  to  make  Bordeaux  mixture  stick  to  the  new 
canes,  and  this  may  possibly  partially  explain  the  failures.  Of 
course  a  thorough  cutting  out  of  the  dead  and  diseased  canes 
soon  after  the  fruiting  season  and  again  in  early  spring  is 
desirable.  It  might  be  well,  too,  to  destroy  any  wild  raspberries 
in  the  immediate  neighborhood. 

TOBACCO,  Nicoiiiana  Tabacum. 
Bed  Rot,   Corticium  vagum  var.   Solani  Burt.      A   special 
study  of  tobacco  diseases  the  past  year  has  brought  to  light  sev- 
eral fungous  troubles  that  have  not  been  reported  before  in  this 
state.     The  Rhizoctonia  stage  of  the  above  fungus,  which  is 
so  common  on  potatoes,  has  recently  been  reported  by  Selby  in 
Ohio  as  the  cause  of  a  bed  rot  of  tobacco.     He  attributed  to  it 
a  dampening  off  of  the  young  plants,  and  cankered  areas  on 
the  stems  of  the  larger  ones.     This  trouble  is  so  similar  to  the 
one  mentioned  in  our  last  Report  and  attributed  to  a  Sclerotinia 
fungus  that  we  afterward  questioned  whether  it  might  not  be 
the  same.     Our  much  wider  examination  of  tobacco  beds  the 
past  year,  however,  seems  to  show  that  the  Sclerotinia  fungus  is 
the  common  dampening  off  agent  in  the  tobacco  seed  beds  in 
this    state.     We   did,    however,    find    the   Rhizoctonia    fungus 
present  in  some  of  the  beds,  but  so  far  as  observed,  its  injury 
was  slight,  and  was  confined,  as  with  the  potato,  to  the  under- 
ground parts.     This  does  not  mean  that  it  may  not  be  as  serious 
a  pest  here  as  in  Ohio,  but  so  far  we  have  not  been  able  to  prove 


NOTES   ON    FUNGOUS    DISEASES   FOR    I906.  325 

definitely  that  it  was  the  cause  of  any  serious  injury.  Since 
it  is  so  well  known  as  a  troublesome  soil  fungus  on  various 
plants,  there  seems  to  be  no  reason  why  it  should  not  be 
responsible  for  some  of  our  tobacco  seed  bed  troubles.  That  it 
is  the  same  fungus  that  occurs  on  potato  was  shown  where 
some  tobacco  plants  were  left  in  the  beds  until  about  the  middle 
of  July,  since  on  tliese  the  Corticium  or  fruiting  stage  of  the 
fungus  formed  a  white  mealy  coating  at  their  base  just  as  it 
does  on  the  potato  stems.  According  to  Selby,  this  fungus  is 
likely  to  develop  most  abundantly  in  an  acid  soil,  so  the  applica- 
tion of  lime  to  such  soils  may  prove  in  part  a  remedial  meas- 
ure. The  general  treatment  for  its  prevention  is  the  same  as 
that  described  later  under  the  Stem  Rot  trouble. 

Canker,  A  Bacterial  Disease?  Plate  XIX,  a,  b.  After 
tobacco  has  attained  considerable  size  in  the  field,  say  from  July 
on,  occasional  plants  are  sometimes  found  that  have  the  stem 
girdled  underground  or  a  cankered  area  reaching  up  a  con- 
siderable distance  on  the  stem,  as  shown  in  the  illustrations. 
In  time  the  bark  of  the  diseased  area  underground  may  entirely 
rot  off,  and  yet  the  plant  above  may  show  the  trouble  only  by 
a  slight  dwarfing  and  a  sickly  yellowish  color  of  some  of  the 
leaves.  The  canker,  when  reaching  above  ground,  shows  a 
dark  brown  sunken  area  in  the  bark  sharply  marked  ofif  from 
its  healthy  green  tissue.  This  trouble  has  been  known  by  the 
growers  in  this  state  for  a  long  time,  but  as  it  occurs  only 
on  an  occasional  plant,  nothing  has  ever  been  published  con- 
cerning it.  In  our  study  of  the  root  rot  trouble  mentioned 
later,  these  cankers  were  noticed,  but  were  believed  to  be  merely 
an  extended  injury  of  the  root  rot,  as  in  the  first  specimens 
examined  that  fungus  was  at  work  on  the  roots  and  also  some- 
what on  the  underground  girdled  area.  Later  experience,  how- 
ever, indicated  that  this  fungus  never  produces  the  cankered 
areas  on  the  stem  above  ground,  at  least  it  was  never  found 
there  in  a  fruiting  condition.  In  these  places,  however,  there 
was  a  more  or  less  prominent  development  of  bacteria,  and 
while  no  special  study  has  been  made  with  them,  it  seems 
probable  that  they  are  the  direct  agents  in  extending  these 
cankers.  No  doubt  root  rot,  stem  rot,  and  even  insect  injuries, 
may  be   the   starting  point  of   these   cankers.      Delacroix   of 


326         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

France  has  recently  described  (Recherches  sur  Quelques  Mala- 
dies du  Tabac  en  France)  a  canker  trouble  of  tobacco  stems 
caused  by  bacteria  that  possibly  may  be  the  same  as  this. 

Dampening  off,  Pythium  sp.  Plate  XXI,  b.  This  fungus 
was  not  found  in  the  regular  tobacco  beds  of  the  state,  though 
probably  it  does  more  or  less  injury  in  them,  but  it  occurred  on 
some  tobacco  seedlings  grown  in  the  Experiment  Station  green- 
house in  rich  loam.  Though  quite  a  different  fungus,  it 
dampens  off  the  young  plants  in  much  the  same  way  as  the 
stem  rot  fungus  described  later,  but  can  generally  be  told  from 
that  trouble  by  the  absence  of  any  white  fungous  threads  creep- 
ing over  the  decayed  plants.  This  fungus  (probably  Pythium 
DeBaryanum  Hesse)  is  a  common  dampening  off  agent  of 
3'Oung  plants  in  greenhouses  and  hotbeds,  especially  if  the  soil 
has  been  used  for  some  time  and  contains  an  abundance  of 
organic  matter  and  moisture.  It  can  be  prevented  by  the  same 
means  employed  against  the  stem  rot  trouble. 

Root  Rot,  Thielavia  hasicola  (B.  &  Br.)  Zopf.  Plates 
XXIX  and  XXXI.  This  was  a  trouble  that  was  very  pro- 
nounced in  certain  tobacco  seed  beds  and  fields  in  the  Connecti- 
cut valley  the  past  year.  While  probably  not  an  entirely  new 
disease  here,  it  certainly  has  not  previously  attracted  the  atten- 
tion it  did  this  year,  and  has  never  before  been  reported  by 
this  Station.  The  injury  occurs  on  the  roots,  which  are  often 
rotted  off  the  young  plants.  In  this  respect  it  differs  entirely 
from  the  dampening  off  troubles  that  rot  the  stem  above  the 
ground.  The  disease  is  discussed  in  detail  in  a  special  article 
in  this  report,  so  no  further  mention  need  be  made  of  it  here. 

Stem  Rot,  Sclerotinia  sp.  Plates  XX,  a-b,  XXI,  a.  This 
is  the  fungus  mentioned  in  our  last  Report  as  a  "Dampening 
Off"  trouble  of  tobacco,  but  as  the  Pythium  fungus  described 
above  usually  goes  by  that  name,  and  has  now  been  found  here, 
its  name  is  changed  to  the  Stem  Rot  trouble.  So  far  as 
observed,  this  is  the  common  trouble  with  tobacco  seedlings 
in  Connecticut.  Its  injury  is  quite  similar  to  that  described 
by  Selby  for  the  bed  rot  caused  by  the  Rhizoctonia  fungus,  and 
both  have  very  similar  sterile  mycelial  threads.  Artificial  cul- 
tures of  the  stem  rot  fungus,  however,  give  rise  to  a  pure  white 
mycelium  which  forms  numerous  small  black  sclerotial  bodies 


NOTES   ON    FUNGOUS   DISEASES   FOR    I906.  327 

that  are  similar  to  those  of  the  drop  fungus  (Sclerotinia 
Libertiana)  of  lettuce,  and  apparently  quite  distinct  from  the 
artificial  cultures  of  the  Rhizoctonia  fungus.  Cultures  made 
from  diseased  plants  obtained  from  the  same  place  in  Bridge- 
water,  Conn.,  both  in  1905  and  1906,  gave  the  same  fungus, 
which  we  have  called  provisionally  Sclerotinia  sp.  In  pass- 
ing, it  might  be  well  to  note  that  Delacroix  of  France  has 
described  a  Sclerotinia  trouble  of  tobacco  which  occurs  on  the 
mature  plants.  Our  fungus  usually  appears  in  spots  in  the  bed, 
dampening  off  all  the  plants  for  some  distance  when  they  are 
crowded  and  the  moisture  is  abundant.  Its  white  threads, 
visible  to  the  naked  eye,  form  a  slight  cobweb-like  coating  on 
the  soil  and  the  base  of  the  plants.  When  the  plants  are  quite 
young,  the  stems  just  above  ground  are  injured  by  a  wet  rot, 
which  causes  the  plants  to  fall  over,  and  eventually  they  are 
entirely  destroyed.  Plate  XX,  a,  shows  a  specimen  where  the 
base  of  the  stem  just  above  ground  was  rotted,  while  the  stem 
above  and  the  roots  below  were  uninjured.  Sometimes  the 
plants  are  so  far  advanced  that  the  tissues  of  the  stem  resist 
the  attack,  with  the  result  that  only  cankered  spots  are  rotted 
in  the  bark,  as  shown  in  Plate  XX,  b,  and  these  may  heal  over 
without  further  injury  from  the  fungus.  Such  plants  are 
sometimes  transplanted  by  accident  in  the  fields,  but  they  do 
not  usually  make  a  satisfactory  development,  as  they  are  often 
broken  off  at  these  cankered  places,  which  also  offer  entrance 
for  other  agents  of  decay. 

The  stem  rot,  like  other  seed  bed  troubles,  is  likely  to  develop 
in  beds  in  which  the  plants  are  too  crowded,  or  kept  too  moist, 
either  by  excessive  watering  or  lack  of  proper  ventilation. 
Care  in  these  respects,  therefore,  will  often  prevent  or  stop  the 
trouble  after  it  is  started,  but  of  course  wet,  cold  springs  often 
make  proper  regulation  of  the  moisture  difficult.  When  the 
trouble  has  been  bad  in  beds  for  a  year  or  two,  it  is  likely  to 
cause  more  or  less  injury  each  season,  and  it  is  then  desirable 
to  either  change  the  beds  or  the  soil  in  them.  Beds  made  in 
low,  wet  spots,  or  which  contain  abundant  organic  matter,  are 
likely  to  be  most  injured  by  this  trouble. 

The  writer  made  a  couple  of  experiments  with  spraying 
diseased  beds  with  weak  formalin  (i  to  1500)  to  see  how  this 


328        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

would  work  in  keeping  down  further  injury  from  the  fungus. 
Part  of  a  bed  at  New  Mil  ford  which  was  sprinkled  twice 
apparently  did  not  show  any  improvement  over  the  rest  of  the 
bed.  In  another  bed  at  Bridgewater,  part  of  which  was 
sprinkled  three  times  in  June,  aftet  the  fungus  had  caused  con- 
siderable injury,  there  was  apparently  some  benefit  from  the 
treatment.  The  writer  did  not  see  plants  from  this  bed  until 
after  they  were  pulled  up,  but  the  owner  and  his  men  said  that 
in  the  treated  part  the  plants  rotted  less,  cankered  spots  healed 
over  quicker,  and  the  fungus  developed  less  prominently  than 
in  the  untreated  part  of  the  bed.  In  certain  beds  at  Hockanum, 
which  had  been  sprinkled  several  times  for  the  root  rot  trouble, 
the  owner  thought  that  the  treatment  had  been  a  benefit.  So 
far  as  the  root  rot  was  concerned,  the  writer  saw  nothing  to 
indicate  that  the  treatment  had  been  helpful,  but  was  inclined 
to  believe  that  possibly  som-e  benefit  had  been  derived  from 
lessening  the  dampening  off  of  the  plants.  While  we  cannot 
state  positively  from  these  experiments  and  observations  that 
sprinkling  the  beds  with  weak  formalin  is  valuable  in  prevent- 
ing stem  rot  and  similar  troubles,  it  seems  well  worth  a  trial 
in  cases  where  the  beds  need  to  be  watered  more  or  less.  In 
such  cases  we  would  advise  the  use  of  weak  formalin  (the 
standard  40  per  cent,  formalin,  diluted  with  water  at  the  rate 
of  I  to  1500)  entirely  in  the  place  of  water.  Such  a  strength 
does  not  seem  to  injure  the  tobacco  seedlings,  and  the  exposed 
fungous  threads  certainly  would  not  develop  in  this  as  they 
would  in  ordinary  water. 

Another  method  of  preventing  this  trouble,  when  one  does 
not  wish  to  change  his  bed,  is  by  sterilizing  the  soil.  This  may 
be  done  either  by  steam  or  formalin.  The  efifect  of  the  for- 
malin treatment  is  shown  in  Plate  XXI,  a.  In  box  i  the  soil 
before  sowing  the  seed  was  thoroughly  soaked  with  a  strength 
of  formalin  at  the  rate  of  i  to  100  of  water;  in  box  2  the 
formalin  was  half  as  strong,  i  to  200;  and  in  box  3  the  soil 
was  merely  soaked  with  water.  These  boxes  were  covered  for 
a  day  to  keep  the  fumes  of  the  formalin  in  the  soil,  and  then 
they  were  uncovered,  aired,  and  the  soil  stirred  to  allow  the 
escape  of  the  formalin.  About  a  week  after  treatment  they 
were  seeded  similarly  with  tobacco.     The  boxes  were  covered 


NOTES   ON    FUNGOUS   DISEASES   FOR    I906.  329 

part  of  the  time  with  glass,  which  kept  the  air  saturated  with 
moisture,  and  as  the  plants  came  up  very  thickly,  the  conditions 
were  excellent  for  the  development  of  dampening  off  troubles, 
except  where  the  fungus  had  been  entirely  killed  in  the  soil. 
At  first  the  two  treated  boxes  were  much  better  than  the 
untreated,  showing  no  dampening  off,  though  the  plants  were 
crowded,  while  the  dampening  off  soon  developed  in  several 
spots  in  the  untreated  box.  Finally,  however,  one  dampening 
off  spot  appeared  in  box  2,  (the  weaker  treatment,  which  appar- 
ently had  not  been  quite  strong  enough  to  entirely  kill  the 
fungus),  and  because  of  the  very  crowded  condition  of  the 
plants  at  this  time,  rapidly  spread  through  the  box,  and  even 
in  time  passed,  at  one  corner  between  the  glass  partition  and 
the  wooden  side,  into  the  box  treated  with  the  stronger  solution. 
The  illustration  shows  the  condition  of  the  three  sets  of  plants 
about  four  weeks  after  seeding. 

This  experiment  shows  that  the  dampening  off  fungi  evi- 
dently can  be  largely  killed  in  the  soil  if  the  formalin  is  strong 
enough  and  the  soaking  of  the  soil  is  thorough.  Based  on  the 
results  of  this  experiment,  two  infected  beds  were  treated  late 
last  fall  at  Bridgewater.  In  these  cases  formalin  was  used  at 
the  rate  of  i  to  100  of  water,  and  the  beds  were  thoroughly 
soaked  by  gradually  sprinkling  on  them  a  gallon  per  square 
foot.  The  beds  were  then  covered  with  gunny  sacks  over  night 
to  keep  in  the  fumes.  Of  course  the  results  of  these  treat- 
ments cannot  be  determined  until  later  in  the  season. 

TOMATO,  Lycopersicum  esculentum. 
Black  Mold,  Fumago  vagans  Pers.  Plate  XVIII,  b.  We 
have  reported  this  fungus  before  on  pears  and  apples,  follow- 
ing attacks  of  plant  lice,  and  also  on  the  linden.  During  the 
past  year  it  occurred  at  the  Experiment  Station  on  tomatoes 
and  nasturtiums  in  the  greenhouse  and  on  tobacco  outdoors, 
in  each  case  following  an  attack  of  tlie  white  fly.  On  these 
various  hosts  the  microscopic  characters  of  the  fungus  were 
not  always  the  same,  as  the  Cladosporium  may  or  may  not  be 
associated  with  an  Alternaria  stage,  or  there  may  be  more  or 
less  of  a  Torula-like  growth.  For  convenience'  we  have  called 
all  of  the  specimens  Fumago  vagans,  since  this  is  the  species 


33°         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

credited  with  growing  in  the  honey  dew  of  insects.  The  most 
striking  development  of  the  fungus  this  year  was  on  tomatoes 
grown  during  the  winter  in  the  greenhouse.  The  white  fly 
confined  its  attack  to  the  underside  of  the  leaves,  while  the 
black  mold  developed  only  on  the  upper  side,  where  it  formed 
a  conspicuous  olive-black  growth,  as  shown  in  the  illustration. 
From  casual  observation  one  would  have  supposed  that  the 
fungus  was  really  an  active  parasite  developing  on  the  tomato, 
quite  similar  to  the  injurious  scab  fungus,  which  often  appears 
on  the  under  surface  of  the  leaves.  The  black  mold  in  reality 
did  not  grow  as  a  parasite,  but  as  a  saprophyte  in  the  honey 
dew  secreted  by  the  fly.  This  honey  dew  evidently  drops  on 
the  upper  surface  of  the  leaves  from  the  insects  on  the  under 
surface  of  the  leaves  above.  This  was  shown  in  the  case  of  a 
tobacco  leaf  where  the  leaf  had  been  partly  folded  on  itself, 
exposing  its  lower  surface  above.  Here  the  black  mold  devel- 
oped on  the  exposed  lower  surface,  and  on  the  upper  surface 
except  where  covered  by  the  fold.  It  is  doubtful  if  the  fungus 
itself  does  any  injury  to  the  leaf  other  than  shutting  ofif  the  sun- 
light, but  it  does  cause  an  unsightly  appearance.  There  is  a 
possibility,  however,  that  such  a  fungus,  after  continued  growth 
on  a  host  in  this  manner,  might  become  parasitic. 

TURNIP,  Brassica  Rapa. 
White  Spot,  Cercosporella  alho-maculans  (E.  &  E.)  Sacc. 
This  fungus  forms  subcircular,  greyish  spots,  showing  on  both 
surfaces  of  the  leaves,  and  varying  from  an  eighth  to  a  quarter 
of  an  inch  in  diameter.  When  abundant  on  the  leaf  it  causes 
premature  yellowing  and  death.  The  disease  was  observed 
last  September  at  Kent  in  a  field  of  turnips,  following  tobacco, 
where  it  was  doing  some  damage.  There  is  some  question 
whether  or  not  this  fungus  is  distinct  from  Cercospora 
Bloxami  B.  &  Br.,  and  in  general  appearance  it  also  resembles 
the  leaf  spot  trouble  of  horseradish  caused  by  a  species  of 
Cercospora. 

VETCH,  RUSSIAN,  Vicia  villosa. 

Leaf  Spot,  Ascochyta  Viciae  Lib.  Plate  XXII,  a.  As  the 
Russian  vetch  has  recently  been  highly  recommended  as  a 
winter  cover  crop  for  tobacco  fields  in  this  state,  any  fungus 
attacking   it  becomes  of   some  economic   importance.     In   one 


NOTES    ON    FUNGOUS    DISEASES    FOR    I906.  33 1 

field  at  Suffield,  in  October  of  the  past  year,  some  plants  of 
this  vetch  were  observed  that  were  being  injured  by  the  above 
leaf  spot  fungus.  This  fungus  forms  subcircular,  greyish 
spots,  with  a  prominent  purplish  border.  The  fruiting  recep- 
tacles are  visible  as  minute  black  bodies  bedded  in  the  center 
of  the  spots,  as  shown  in  the  illustration.  As  the  leaflets  are 
small  only  one  or  two  spots  generally  appear  on  each,  but  these 
are  often  sufficient  to  cause  their  premature  death.  The  fungus 
has  been  reported  before  in  this  country  by  Ellis,  on  the  pods 
of  this  same  host,  and  also  from  Canada,  on  the  leaves  of  a 
different  species  of  vetch.  Saccardo  lists  Ascochyta  Pisi, 
a  common  fungus  of  the  pea,  on  the  Russian  vetch,  and  as 
this  fungus  is  very  similar  to  the  species  reported  here,  there 
may  be  some  question  as  to  their  distinctness. 

VIOLET,   Viola  sps. 

Speck  Anthracnose,  Marsonia  Violae  (Pass.)  Sacc,  Plate 
XXII,  b.  We  have  previously  reported  a  number  of  leaf  dis- 
eases of  greenhouse  violets.  The  above  is  one  that  has  rarely 
been  reported  in  the  United  States.  It  v/as  sent  from  Niantic 
last  fall  by  Miss  Angle  M.  Ryon,  who  reported  considerable 
injury  to  various  species  of  native  violets  which  she  was  cul- 
tivating for  scientific  purposes.  The  trouble  differs  chiefly 
from  the  other  leaf  troubles  of  violets  so  far  reported  in  the 
very  small  size  of  the  reddish  spots,  which  are  usually  smaller 
than  a  pin  head.  The  spots,  however,  may  become  very  abun- 
dant, being  scattered  or  clustered,  and  cause  a  yellowing  of  the 
intervening  tissues  and  serious  injury  to  the  leaves. 


332        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 


II.    EXPERIMENTS  TO  PREVENT  ONlON  BRITTLE. 

Nature  of  injury.  In  our  last  Report  we  described  a  peculiar 
disease  of  onions,  called  brittle,  that  was  reported  by  Burton 
W.  Bishop  of  Guilford  as  being-  a  serious  trouble  in  that  vicinity 
when  once  it  became  established  in  a  field.  Our  investigations 
at  that  time  indicated  that  the  trouble  was  caused  by  a  soil 
fungus  that  worked  especially  in  the  roots  but  whose  identity 
was  not  fully  established.  The  past  season  we  made  some 
successful  experiments  to  prevent  this  trouble  but  gained 
little  further  information  concerning  its  cause,  partly  because 
of  its  obscurity  but  chiefly  because  this  side  of  the  investigation 
was  not  especially  considered.  The  general  character  of  the 
disease  is  briefly  given  in  the  following  paragraph,  but  a 
somewhat  fuller  account  may  be  found  on  pages  270-3  of  the 
Experiment  Station  Report  for  1905. 

The  trouble  usually  starts  in  some  small  section  of  a  field 
and  each  year  extends  out  further,  so  that  the  land  eventually 
becomes  of  little  value  for  growing  onions.  Weeds  in  the 
infected  area  also  do  poorly.  In  some  respects  the  trouble 
resembles  an  acid  soil,  and  yet  this  could  hardly  explain  the 
spreading  of  the  trouble  or  the  benefit  that  resulted  from  the 
use  of  certain  soil  fungicides.  While  apparently  caused  by 
a  fungus,  this  is  never  evident  externally  on  the  roots  and  often 
it  does  not  seem  abundant  enough  within  their  tissues  to 
cause  so  prominent  an  injury.  Though  not  definitely  deter- 
mined by  actual  observation,  apparently  many  of  the  very 
young  seedlings  are  dampened  off  or  killed  outright,  since  the 
stand  in  the  infected  area  is  usually  very  poor  and  irregular. 
In  fact  most  of  the  injury  seems  to  be  to  the  seedlings,  though 
the  older  plants  do  not  entirely  recover  from  the  backset  they 
received.  The  infected  plants  are  much  smaller  than  the 
healthy  ones  near  them  or  those  in  the  part  of  the  field  free 
from  the  disease,  as  is  shown  in  Plate  XXIII,  a.  Another 
peculiarity  is  the  brittleness  of  the  leaves,  from  which  the 
trouble  takes  its  name.  Very  often  the  leaves  are  quite  irreg- 
ular or  have  peculiar  spiral  coils  as  shown  in  h  of  this  same 
plate.  The  onions  may  also  have  a  sickly  yellowish  green 
color,  especially  in  spots,  instead  of  the  normal  dark  green. 


EXPERIMENTS   TO    PREVENT    ONION    BRITTLE.  333 

PREVENTIVE  EXPERIMENTS. 

Nature  of  experiments.  Through  the  courtesy  of  Mr. 
Bishop,  one  end  of  his  field  was  used  in  1906  for  experiments 
in  preventing  the  onion  brittle.  The  disease  showed  first  in 
this  field  two  years  before  and  when  seen  by  the  writer  in  1905 
had  infected  an  irregular  area  in  one  corner  about  two  or 
three  rods  each  way.  In  1906  this  infected  spot  had  greatly 
extended  itself,  in  one  direction  spreading  nearly  across  the 
field,  though  tapering  out  toward  the  further  end.  The 
character  of  the  infected  area  is  shown  in  Plate  XXIV,  a, 
which  slightly  exaggerates  the  injury  to  the  onions  in  1906 
since  some  plants  did  come  up  on  the  vacant  place,  but  these 
were  so  few  and  scattered  that  they  were  finally  plowed  up  as 
worthless. 

As  the  trouble  is  in  tlie  soil  and  injures  the  plants  chiefly 
while  young,  the  treatments  were  made  v^^ith  this  in  view.  In 
the  comer  of  the  field  where  the  trouble  first  showed,  the 
ends  of  one  to  seven  rows  (each  53  feet  long  and  14  inches 
apart  and  so  representing  about  one  seven-hundredths  of  an 
acre)  were  used  for  each  treatment.  The  first  set  of  treat- 
ments, made  at  the  time  of  seeding,  April  20,  was  as  follows : 

Plot.  No.  Rows.  Treatment. 


1 6  (.1-6)... 

2 4(7-10).. 

3 I  (11)  ■•• 

4 7(12-18). 

5 7(19-25). 


Check  ;  no  treatment. 

Formalin  (i  to  240  water)  at  rate  of  525  gals,  per  acre. 
Limoid  at  rate  of  700  lbs.  per  acre. 
Sulphur  and  limoid  (2  to  i)  at  rate  200  lbs.  per  acre. 
Complete  fertilizer  (i  sol.  bone  black,  i  mur.  pot.,  2;^ 
sod.  nitr.)  at  rate  of  650  lbs.  per  acre. 
6 00  (26-00).  .      Check  ;  no  treatment. 


In  each  case  after  the  seed  was  sown  the  fungicide  was 
sprinkled  or  scattered  over  it  and  the  adjacent  earth  before 
covering.  In  this  way  the  rates  used  were  much  more  effective 
than  if  the  fungicides  were  scattered  broadcast.  The  fertilizer 
was  scattered  directly  over  the  rows  after  the  seed  was  covered. 
This  complete  fertilizer  was  used  partly  to  determine  if  the 
land  was  lacking  in  fertility  but  chiefly  to  see  if,  with  quickly 
available  food,  the  young  plants  could  be  forced  to  a  rapid 
development  and  so  outgrow  or  escape  the  injurious  action  of 
the  fungus  which  seems  to  attack  the  plants  most  injuriously 
while  quite  small.  The  land,  however,  had  already  been  well 
fertilized,  since  Mr.  Bishop  used  at  about  the  rate  of  9  tons 


334         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

of  salt  hay,  Yz  ton  fish  scrap  and  3  tons  wood  ashes  per  acre.- 
He  used  the  salt  hay,  partly  composed  of  sea  weed,  to  get 
more  humus  in  the  soil  and  because  he  thought  that  the  salt 
might  have  some  influence  in  checking  the  brittle. 

On  June  9th,  after  the  plants  had  made  considerable  growth, 
a  second  set  of  experiments  (similar  lengths  of  two  rows  in 
each  case)  was  made  to  determine  if  the  treatments  would 
have  any  effect  in  stopping  or  lessening  the  trouble  after 
it  once  showed  in  the  plants.  These  treatments  were  with 
limoid  (700  lbs.  per  acre),  ground  fresh  lime  (700  lbs.  per 
acre),  air  slaked  lime  (700  lbs.  per  acre),  fresh  lime  slaked 
in  water  (^^  lb.  to  2  gals,  water  used  at  rate  1400  gals,  per 
acre),  and  formalin  (i  to  1500  water  in  two  applications  at 
rate  each  of  1400  gals,  per  acre).  These  rows  all  showed  at 
this  time  considerable  injury  from  the  brittle,  especially  in  the 
poor  stand. 

Results  of  experiments.  The  onions  in  the  second  set  of 
experiments  (those  treated  after  the  plants  showed  the  disease) 
in  no  case  at  any  time  showed  any  very  appreciable  benefit  from 
the  treatments.  This  indicates  that  the  injury  to  the  onions  is 
caused  primarily  while  they  are  quite  small,  or  at  least  that 
this  is  the  time  of  infection,  and  so  any  treatment  to  be  effective 
must  be  made  at  the  time  of  seeding. 

In  the  first  set  of  treatments,  made  at  the  time  of  seeding, 
the  effect  was  quite  evident  soon  after  the  plants  appeared 
above  ground.  The  first  examination  by  the  writer,  made  on 
June  4,  showed  that  the  stand  and  size  of  the  plants  were  much 
better  in  all  of  the  plots  treated  with  formalin,  limoid,  sulphur 
and  limoid  than  in  the  untreated  plots  and  were  practically  the 
same  as  the  plants  in  the  best  parts  of  the  uninfected  portion 
of  the  field.  The  weeds,  too,  which  had  been  left  for  obser- 
vation, were  much  more  numerous  and  thrifty  in  these  treated 
plots  than  in  the  untreated.  The  relative  size  of  the  diseased 
and  healthy  plants  at  this  time  is  shown  in  Plate  XXIII,  a.  The 
plot  on  which  the  complete  fertilizer  had  been  placed  was  not 
any  better  than  the  worst  of  the  infected  rows  that  had  not 
been  treated  at  all.  This  showed  plainly  that  the  trouble  was 
in  no  way  due  to  an  impoverished  soil  or  that  the  young  plants 
could  be  stimulated  in  growth  to  escape  the  trouble.  Of  the 
check  plots.  No.  i,  which  was  on  the  very  edge  of  the  field, 
was  much  better  than  No.  6,  which  made  such  a  poor  stand 


EXPERIMENTS    TO    PREVENT    ONION    BRITTLE.  335 

that  the  onions  were  worthless.  Check  plot  No.  i,  however, 
was  not  as  good  as  any  of  the  treated  rows,  but  was  consider- 
ably better  than  the  plot  with  the  complete  fertilizer. 

On  July  12  the  second  examination  was  made  and  about  the 
same  relative  condition  of  the  plots  was  found.  The  striking 
difference  between  the  treated  plots  (limoid,  sulphur  and  limoid, 
and  formalin)  and  the  untreated  plots  (complete  fertilizer  and 
check  plot)  is  shown  in  Plate  XXIV,  b.  This  photograph  shows 
chiefly  the  sulphur  and  limoid  and  the  complete  fertilizer  plots 
and  it  brings  out  the  sharp  differentiation  in  size  and  number 
of  plants  even  in  their  two  adjacent  rows.  A  more  detailed 
view  of  the  treated  and  untreated  plants  is  given  in  Plate 
XXV.  In  a  is  shown  plants  in  the  complete  fertilizer  plot 
while  in  b,  photographed  at  the  same  time  and  size,  is  shown 
a  row  each  in  the  sulphur  and  limoidj,  limoids,  and  formalin2 
plots. 

The  crop  was  harvested  on  Sept.  7,  when  the  number  and 
weight  of  the  onions  in  each  plot  was  determined.  As  a  whole 
the  season  was  very  unfavorable  for  onions,  so  that  the  differ- 
ence in  yield  due  to  the  treatment,  possibly,  was  not  so  great 
as  it  would  have  been  in  a  more  favorable  season.  The  treated 
plots  gave  practically  the  same  yield  as  the  uninfected  part  of 
the  field.  Mr.  Bishop  considers  400  bushels  per  acre  a  good 
yield  for  this  field  during  a  favorable  season,  but  this  year 
only  about  half  this  was  obtained.  The  following  table  gives 
the  details  of  the  yields  in  the  different  plots. 

Yield  oj"  A  Terage  per  A  it.  per 

Onions.  row  S3ft.  acre. 

Plot.  Treatment.  No.  Lbs.  No. 


Check 920...      54>^---      I53-- 

Formalin 1161...     bo)^ . . .     290.. 

Limoid 268...      15 268.. 

Sulphur  and  limoid. .. .     2072...     99^...      296.. 
Complete  fertilizer  (check) 35 . . 


Lbs. 

Bu. 

.         9... 

121. . . 

.      i5i.. 

205. . . 

.      15... 

202. . . 

.      I4i.. 

191... 

.      ^%.. 

15... 

The  complete  fertilizer  plot,  X^o.  5,  and  the  check  plot.  No.  6, 
were  both  practically  alike  and  so  poor  as  to  be  worthless ;  so 
the  yield  from  the  single  row  given  here  probably  represents 
about  an  average  for  these  and  the  worst  part  of  the  infected 
field.  It  is  readily  seen  from  this  table  that  the  treatments 
considerably  increased  the  yield  over  the  best  of  the  untreated 
rows  and  as  the  larger  part  of  the  infected  area  was  similar  to 
plot  5  the  increase  in  reality  was  very  considerable. 


336        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

III.     DRY  ROT  FUNGUS, 
Merulius  lacrymans  (Wulf.)  Schum. 

Timber-destroying  fungi  in  general.  Both  parasitic  and 
saprophytic  fungi  cause  injury  to  our  commercial  forest  trees, 
the  former  doing-  damage  to  the  living  trees,  and  the  latter 
producing  decay  of  their  wood  after  they  have  died  from  vari- 
ous causes.  Apparently  the  financial  loss  caused  by  the  latter 
class  is  much  greater  than  that  of  the  former.  Such  fungous 
injuries  in  this  country  have  been  studied  extensively  by  von 
Schrenk  of  the  United  States  Department  of  Agriculture,  who 
has  issued  several  bulletins  dealing  with  special  troubles  of 
certain  kinds  of  timber  trees  and  their  lumber.  Popular 
articles  upon  fungous  injuries  to  trees  have  also  been  written 
from  time  to  time  by  other  American  botanists.  Most  of  the 
injuries  to  trees  by  fungi  are  caused  by  certain  species  belong- 
ing to  a  group  known  technically  as  the  Hymenomycetes,  of 
which  the  toadstools  and  shelf  fungi  are  familiar  examples. 

In  the  present  article  we  discuss  an  injury,  caused  by  one  of 
these  fungi,  to  the  timber  after  it  had  been  placed  in  a  building. 
This  dry  rot,  or  house  fungus,  is  peculiar  in  that  it  is  what 
might  be  called  a  domesticated  fungus ;  that  is,  it  rarely,  if 
ever,  causes  rot  of  the  trees  in  the  forests.*  Mention  has  been 
made  in  this  country  of  slight  injuries  caused  by  this  fungus  to 
the  woodwork  of  cellars,  greenhouses,  etc.,  where  the  moisture 
had  been  favorable  for  its  development,  and  short  popular 
articles  concerning  the  fungus  itself  have  been  written  by  Mac- 
Bride,  Freeman  and  Atkinson ;  but  the  writer  has  found  no 
extended  notice  of  serious  injury  caused  by  it.  Mr.  A.  B. 
Seymour,  in  a  recent  letter,  writes  that  some  years  ago  he 
examined  the  rafters  of  a  noted  old  church  in  Boston,  and  found 
them  considerably  injured  by  dry  rot,  which,  however,  was 
then  entirely  inactive.     He  also  wrote  that  he  was  informed 


*Appel  (Arb.  K.  Biol.  Anst  Land.  Forstw.  5:  204-6.  1906)  recently- 
tried  to  infect  seedlings  of  fir  and  pine,  grown  in  pots  in  the  greenhouse, 
by  introducing  the  mycelium  through  -wounds  in  the  stems;  and  -while 
he  did  obtain  a  growth  of  Merulius  lacrymans  this  in  no  way  seemed 
to  be  parasitic  on  the  trees. 


DRY    ROT    FUNGUS.  337 

that  the  house  at  Cambridge  in  which  OHver  Wendell  Holmes 
was  born  was  so  injured  by  dry  rot  that  it  could  not  be  moved, 
and  so  had  to  be  torn  down  to  make  way  for  the  Hemenway 
Gymnasium.  In  Europe,  however,  where  the  literature  relat- 
ing to  this  fungus  is  more  extensive,  serious  injury  to  buildings 
has  been  reported  a  number  of  times.  The  specific  case 
described  in  this  article  is  of  injury  to  North  Carolina  pine  in 
the  basement  of  a  church,  and  was  called  to  the  writer's  attention 
the  past  summer  by  ex-Senator  William  J.  Clark  of  Stony 
Creek.  The  writer  made  several  trips  to  Stony  Creek  to  observe 
the  fungus  and  its  injury,  and  is  indebted  to  Mr.  Clark  for 
information  concerning  its  first  appearance,  etc. 

INJURY  BY  DRY  ROT  FUNGUS  TO  W^OODWORK  OF  A  CIIURCH. 

General  situation.  The  trouble  was  called  to  our  attention 
about  the  middle  of  June,  the  first  examination  being  made  the 
29th  of  that  month.  This  stone  church  was  comparatively  new, 
and  a  corner  of  the  basement  had  recently  been  partitioned  off 
for  a  Sunday  school  room.  The  entrance  to  this  room  and  the 
basement  was  from  a  tower  vestibule  above,  that  also  led  into 
the  main  auditorium.  The  steps  leading  down  to  the  Sunday 
school  room  were  enclosed  in  a  narrow  passageway.  It  was 
under  these  steps,  close  to  the  entrance  of  the  Sunday  school 
room,  that  the  trouble  was  first  noticed  in  an  inconspicuous  way, 
some  months  previous  to  our  visit,  through  the  rotting  of  a 
few  of  the  boards.  These  boards  had  been  replaced,  and  noth- 
ing more  was  seen  of  the  trouble  until  after  the  furnace  fire 
was  discontinued  in  the  spring.  The  walls  of  the  Sunday 
school  room  are  formed  on  two  sides  by  the  stone  foundations 
of  the  church,  and  on  the  other  two  sides  by  a  board  partition 
separating  it  from  the  remainder  of  the  basement,  which  is  used 
as  a  furnace  and  fuel  room.  The  Sunday  school  room  was 
plastered  to  the  floor  directly  on  the  stone  on  two  sides,  and  on 
lath  on  the  other  two  sides.  The  baseboard  and  wainscoting, 
of  North  Carolina  pine  in  natural  finish,  covered  the  plastering 
to  a  height  of  three  or  four  feet  all  around  the  room.  The 
back  of  the  board  partitions  on  the  furnace  side  of  the  base- 
ment was  sealed  tight  by  unpainted  boards.  The  steps  lead  into 
the  Sunday  school  room  at  one  corner ;  beneath  these  is  a  small 
24 


33^        CONNECTICUT    EXPERIMENT    STATION    REPORT,     I906. 

dark  closet  opening  into  this  room,  and  nearby  in  the  wooden 
partition  a  pair  of  swinging  doors  leading  into  the  furnace  room. 
It  was  in  this  corner  (see  Plate  XXVI)  under  the  steps  (where 
the  trouble  originally  showed)  and  in  the  closet  that  the  fungus 
started  with  renewed  vigor  in  the  spring.  At  the  time  of  our 
visit,  a  month  or  two  after  the  first  signs  of  its  renewed  attack 
were  noticed,  it  had  spread  on  one  side  along  the  wooden  parti- 
tion, past  the  swinging  doors,  for  a  distance  of  about  fifteen 
feet;  but  on  the  other  side  of  the  steps,  along  the  stone  wall, 
only  a  very  short  distance.  Only  one  or  two  small  isolated 
outbreaks  were  found  elsewhere,  showing  on  the  furnace  room 
side  on  a  sill  that  rested  on  the  damp  earth.  Fortunately  the 
floor  of  the  Sunday  school  was  cement,  for  no  doubt  if  wooden 
the  fungus  would  have  found  a  very  favorable  condition  for 
its  development  beneath  it.  The  furnace  room  had  no  floor, 
but  contained  piles  of  old  boards  for  fuel,  and  in  a  number  of 
cases  where  the  boards  rested  directly  on  the  damp  ground, 
there  was  a  slight  development  of  the  fungus. 

Conditions  favoring  development.  In  Europe  there  have 
been  cases  where  this  trouble  developed  in  buildings  apparently 
because  the  wood  used  in  their  construction  was  already 
infected  with  the  fungus.  In  the  present  instance  however, 
this  does  not  appear  to  have  been  the  case,  for  apparently  the 
fungus  started  from  infected  old  boards  in  or  under  the  steps, 
and  afterwards  spread  to  the  new  lumber  because  of  the  very- 
favorable  conditions  for  its  development.  While  this  is  called 
the  dry  rot  fungus,  it  really  requires  moisture  for  its  develop- 
ment, which  was  very  thoroughly  provided  in  the  present 
instance.  During  the  winter,  while  the  furnace  was  going,  the 
fungus  gave  no  evidence  of  its  development,  if  present  between 
the  wainscoting  and  the  plastering.  After  the  ordinary  damp 
spring  months  came  an  unusually  wet  June,  with  very  frequent 
heavy  rain  storms.  These,  together  with  the  situation  of  the 
church  on  a  rock  close  to  the  Sound,  made  the  moisture  very 
evident  in  the  basement.  Then,  too,  the  basement  was  cool, 
and  so  tended  to  condense  moisture  from  the  saturated  atmos- 
phere on  the  woodwork.  The  leaders  on  this  side  of  the 
church  did  not  carry  the  water  away  from  the  foundation,  and 
on  the  other  side  there  was  no  eave  trough.  This  made  the 
ground   around  the  basement   Sunday   school   room   very   wet 


DRY    ROT    FUNGUS.  339 

during  the  frequent  rains.  The  effect  of  the  abundant  moisture 
was  shown  by  the  warping  of  the  wainscoting  even  where  there 
was  no  sign  of  the  fungus  at  work.  The  fact  that  the  plaster- 
ing extended  down  to  the  floor  under  the  wainscoting  and  that 
the  back  was  sealed  up  was  also  most  favorable  for  the  develop- 
ment of  the  fungus  along  the  wooden  partition,  since  here  was 
an  enclosure  that  prevented  its  damp  atmosphere  from  readily 
drying  out  during  the  dry  weather.  Lastly,  the  slight  space 
between  the  back  of  the  wainscoting  and  the  plastering  fur- 
nished a  most  admirable  place  for  the  rapid  development  of  the 
fungus  along  the  wall. 

Character  of  the  fungous  growth.  The  fungus  consists  of 
three  parts:  (a)  the  mycelium,  which  penetrates  into  the  tis- 
sues of  the  wood,  and  causes  its  decay ;  (b)  sterile  mycelial 
strands  that  develop  on  the  surface  of  the  boards,  on  the 
protected  side,  and  serve  as  a  means  for  rapidly  spreading  the 
fungus  from  one  point  to  another;  and  (c)  the  fruiting  stage, 
formed  by  a  luxuriant  development  of  fertile  hyphae  into 
special  bodies  bearing  the  spores,  or  reproductive  bodies,  on 
their  surface.  The  mycelium  consists  of  branched  microscopic 
threads  that  penetrate  into  the  wood  between  and  into  the  cells, 
and,  according  to  Hartig,  dissolve  out  the  coniferin  and  cellu- 
lose of  their  walls,  which  causes  the  cells  to  become  very  fragile. 
In  fact,  in  time  the  wood  may  crack  up  into  little  areas  as  it 
dries  out,  and  eventually  is  easily  crushed  into  a  fine  powder 
between  the  fingers.  The  mycelial  strands  are  usually  in  the 
shape  of  a  flat  mat,  with  meshes  of  irregular  size  and  shape 
(see  Plate  XXVII,  b).  Where  the  fungus  showed  prominently 
on  the  exterior  of  the  woodwork,  these  flat  strands  thickly 
covered  the  under  side  of  the  boards  and  even  the  plastering,  as 
shown  in  Plate  XXVII,  a.  They  have  a  greyish  color,  and  a 
growing  margin  of  a  whitish,  fluffy  texture,  as  shown  on  the 
wall  in  the  same  illustration.  In  some  cases,  especially  on  the 
ground,  or  where  the  conditions  for  growth  were  limited,  the 
sterile  mycelium,  instead  of  forming  a  mat,  took  the  shape  of 
cords  or  strands,  and  these  often  grew  for  a  considerable  dis- 
tance. Such  strands,  by  creeping  through  obscure  or  inac- 
cessible places,  under  the  sills,  etc.,  offer  a  very  dangerous 
means  for  spreading  the  fungus  to  other  portions  of  the  build- 
ing.    When  the  moisture  conditions  of  the  room  became  favor- 


34°        CONNECTICUT    EXPERIMENT    STATION    REPORT,     I906. 

able  during  the  very  wet  weather  of  June,  the  fungus  began 
to  show  its  presence  by  emerging  between  the  boards  of  the 
wainscoting  and  around  the  woodwork  of  the  closet  and  the 
swinging  door,  and  developing  its  fruiting  stage.  This  out- 
growth was  quite  conspicuous,  and  appeared  very  rapidly  (see 
Plate  XXVI).  The  growth  at  first  was  a  fluffy  mat  of  the 
white  mycelium,  which,  after  appearing  in  the  cracks,  spread 
out  on  either  side  for  an  inch  or  two  in  width  and  for  a  much 
longer  distance  along  the  crack.  While  these  immature  fruiting 
mats  when  fresh  were  an  inch  thick,  when  dried  out  they 
became  quite  thin  and  leathery.  At  first  they  were  white,  and 
without  folds ;  but  soon  they  began  to  turn  a  reddish  brown, 
due  in  part  to  the  formation  of  the  colored  spores.  Where  they 
had  a  chance  to  fully  mature,  their  surface  became  sculptured 
with  irregular  folds  or  corrugations,  or  sometimes  with  flat, 
tooth-like  projections,  after  the  usual  manner  of  the  fructifica- 
tion of  the  genus.  Plate  XXVIII  shows  at  a  some  of  the 
immature  fruiting  bodies  on  a  piece  of  the  wainscoting,  while 
at  h  the  mature  fruiting  bodies  are  shown. 

Damage  caused.  The  rapidity  with  which  the  fruiting  stage 
of  the  fungus  developed  during  the  favorable  weather  of  June 
is  shown  in  Plate  XXVI.  The  growth  as  shown  in  a  had  all 
been  scraped  off  a  week  or  so  before  this  photograph  was  taken, 
while  h  shows  the  condition  just  twelve  days  after  the  first 
photograph  was  made.  The  fungus  was  so  prominent  at  this 
time,  and  its  injury  so  great,  that  the  trustees  of  the  church 
decided  to  remove  all  the  infected  woodwork.  Many  of  the 
boards  of  the  wainscoting  were  very  badly  rotted,  while  others 
were  so  badly  infected  that  it  was  only  a  question  of  time 
before  they  would  be  in  the  same  condition.  There  was  danger, 
too,  of  the  fungus  spreading  to  the  remainder  of  the  woodwork, 
and  even  above  into  the  church  proper.  European  writers 
mention  cases  where  the  fungus,  starting  in  a  wet  basement, 
has  spread  up  into  the  second  story  even  when  that  part  of  the 
building  was  dry.  The  fungus  can  do  this  easily  by  means  of 
its  long  sterile  strands,  which  also  carry  food  and  moisture  for 
its  development.  Often  this  moisture  is  given  off,  and  wets 
surrounding  objects,  as  the  plastering  in  the  present  case  in 
one  place  well  up  on  the  wall.  On  account  of  this  characteris- 
tic, the  specific  name  lacrymans  (weeping)  has  been  given  to 


DRY    ROT    FUNGUS.  34 1 

the  fungus.  The  actual  damage  in  the  present  case  was  per- 
haps less  than  one  hundred  dollars,  but  there  was  also  the 
danger  of  possible  future  attacks,  which  might  be  even  more 
serious,  especially  if  the  fungus  worked  into  the  main  part  of 
the  church. 

Preventive  measures.  At  the  suggestion  of  the  writer,  all 
of  the  infected  woodwork  was  cut  out,  and  even  the  plastering 
and  laths  were  removed  where  the  fungus  showed.  The  lower 
boards  on  the  sealed  side  of  the  furnace  room  were  also  taken 
off  to  allow  a  circulation  of  air  between  the  partitions.  All  the 
infected  material  was  destroyed,  and  the  basement  was  also 
cleaned  of  all  rubbish.  The  drainage  was  carried  away  from 
the  walls  of  the  church  to  keep  these  from  becoming  damp. 
On  July  2 1st,  after  the  diseased  wood  had  been  removed,  the 
writer  thoroughly  sprayed  the  ground,  plastering,  and  boards 
near  where  the  fungus  had  been  at  work,  using  water  contain- 
ing two  per  cent,  of  formalin  and  two  per  cent,  of  carbolic  acid. 
This  was  done  in  order  to  kill  any  scattered  spores  or  superfi- 
cial mycelial  strands  that  might  have  escaped  notice.  That  this 
spray  was  effective  against  exposed  mycelia  was  shown  by 
spraying  part  of  a  badly  infected  board.  This  was  then  sawed 
in  two,  and  the  sprayed  and  unsprayed  pieces  were  placed  for 
some  time  in  a  moist  chamber.  The  sprayed  half  never  made 
any  growth  of  the  fungus,  except  a  slight  development  on  the 
cut  end  of  the  board  from  the  deeply  imbedded  fungus  threads. 
On  the  unsprayed  board,  however,  the  fungus  developed 
abundantly. 

The  partition  has  not  yet  been  replaced,  being  left  out  to 
see  if  the  fungus  will  develop  any  further.  At  this  date 
(March  15th,  1907)  it  has  showed  no  signs  of  reappearing. 


342        CONNECTICUT    EXPERIMENT    STATION    REPORT,    IC)o6. 

IV.  ROOT  ROT  OF  TOBACCO, 
Thielavia  hasicola  (B.  &  Br.)  Zopf. 

GENERAL    CONSIDERATION    OF    THE    TROUBLE. 

Discovery  of  the  trouble  in  Connecticut.  During  the  past 
season  a  serious  root  disease  of  tobacco  has  been  prevalent  in 
certain  seed  beds  and  fields  in  this  state.  While  probably  not 
an  entirely  new  trouble,  it  certainly  has  not  heretofore  attracted 
any  special  attention  among  tobacco  growers.  Neither  has  the 
fungus  [Thielavia  hasicola  (B.  &  Br.)  Zopf]  causing  it  been 
previously  reported  on  tobacco  by  the  botanists  of  this  station, 
though  Thaxter  in  1891  found  it  causing  serious  injury  to 
violets.  Mr.  Shamel,  of  the  United  States  Department  of 
Agriculture,  who  is  cooperating  with  this  station  in  a  study 
of  the  improvement  of  tobacco  by  selection  and  breeding,  was 
the  first  to  report  it  on  this  plant  in  the  state.  In  an  interview 
with  Mr.  Shamel  printed  in  the  Hartford  Daily  Courant  of 
May  28,  1906,  attention  was  called  to  the  serious  injury 
caused  by  the  root  rot  in  the  tobacco  beds  of  the  Connecti- 
cut valley.  It  was  also  stated  in  this  article,  apparently  from 
personal  observations,  that  this  disease  had  proved  a  very 
serious  pest  in  Cuba,  and  had  spread  to  an  alarming  extent 
all  over  the  tobacco-growing  districts  of  America.  Mr.  Shamel 
strongly  recommended  sprinkling  the  seedlings,  in  seed  beds 
showing  the  trouble,  with  formalin.  In  view  of  this  serious 
report,  which  was  partially  copied  in  a  number  of  papers  over 
the  state,  and  because  of  its  especial  interest  in  the  tobacco 
industry,  this  station,  through  its  director  and  botanist,  made  a 
careful  study  of  the  diseased  seed  beds  and  the  fields  during  the 
remainder  of  the  season.  There  is  given  here  a  complete  report 
of  this  investigation.* 

History  elsewhere.  The  fungus  responsible  for  this  trouble 
was  first  described  from  England  by  Berkeley  and  Broome 
in  1850.     They  reported  it  as  a  probable  parasite  on"  the  base 


*  A  preliminary  report  (6)  of  the  investigation  was  made  by  the 
Director  and  the  Botanist  in  Bulletin  of  Immediate  Information,  No.  4, 
of  this  Station. 


ROOT    ROT   OF   TOBACCO.  343 

of  the  stems  of  peas  and  another  plant.  Zopf,  of  Germany, 
in  1876,  however,  was  the  first  to  give  a  complete  account  of 
the  different  stages  of  the  fungus.  He  found  it  injuring  the 
roots  of  a  species  of  Senecio,  and  some  years  later  also  on 
the  roots  of  a  number  of  leguminous  plants.  Thaxter  was 
the  first  to  report  the  fungus  from  America,  having  found  it, 
as  previously  stated,  on  the  roots  of  violets  in  this  state. 
Peglion  was  apparently  the  first  to  find  the  fungus  injuring 
tobacco.  In  1897  he  made  a  report  of  injury  to  the  roots  of 
tobacco  in  the  fields  of  Italy.  He  thought  that  the  water- 
clogged  condition  of  the  soil  was  in  part  responsible  for  the 
serious  injury  done  by  the  fungus.  Selby,  of  the  Ohio  Experi- 
ment Station,  was  the  first  to  find  the  fungus  on  tobacco  in 
the  United  States,  having  seen  diseased  specimens  from  seed 
beds  as  early  as  1899. 

Nature  of  the  fungus.  There  seems  to  have  been  doubt  in 
the  minds  of  some  of  the  investigators  as  to  the  exact  parasitic 
nature  of  the  fungus.  In  the  first  place  it  belongs  in  a  family 
of  fungi  that  consists  chiefly  of  saprophytic  forms,  having  a 
few  weak  parasites.  The  other  two  species  that  have  been 
placed  under  the  genus  Thielavia  are  both  saprophytes,  one 
having  been  found  on  dung  and  the  other  on  dead  stems  of 
Carduus.  The  fact  that  the  fungus  occurs  on  the  roots  also 
tends  to  obscure  its  true  nature  and  apparently  at  times  to 
induce  a  saprophytic  existence. 

Berkeley  (2)  said  of  the  fungus:  "It  is  either  destructive 
of  the  plant  on  which  it  grows  or  is  developed  on  it  in  conse- 
quence of  previous  disease."  Zopf  (24)  considered  it  a  true 
parasite  producing  characteristic  injuries  to  the  roots,  which  he 
called  "Wurzelbraune."  Sorauer  (17)  concluded  that  it  led 
a  saprophytic  as  well  as  a  parasitic  existence,  as  he  found  it 
developing  on  certain  leafmolds,  and  he  also  stated  that  it  might 
occur  in  the  soil  at  times  without  doing  injury  to  the  roots  of 
plants  grown  there.  Peglion  (9),  as  we  have  already  stated, 
thought  that  unfavorable  conditions  for  root  development,  a 
water-clogged  condition  of  the  soil,  influenced  its  attack  on  the 
field  tobacco  in  Italy.  Selby  (13)  while  noting  that  the  fungus 
caused  evident  injury  in  the  seed  beds,  stated  that  "the  field 
development  of  the  trouble  remains  open  for  study  with  us." 
Aderhold    (i),  who  made  some  infection  experiments,   failed 


344        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

to  infect  Begonia  semperflorens,  though  his  cultures  originally 
were  obtained  from  a  diseased  Begonia,  but  he  did  succeed  with 
several  other  species.  He  was  able  in  these  cases,  however,  to 
produce  the  disease  only  at  the  crown  of  the  plants.  This 
seems  peculiar  since  with  tobacco  it  is  the  rootlets  that  were 
found  most  injured.  It  is  quite  probable,  however,  that  if 
infection  experiments  were  carried  on  with  seedlings  that  the 
roots  would  be  readily  infected.  Aderhold  agrees  with 
Sorauer  that  the  fungus  becomes  an  aggressive  parasite  only 
under  certain  favorable  conditions.  Shamel  (15)  evidently 
considered  it  a  very  injurious  and  aggressive  parasite. 

In  Connecticut  some  of  the  growers  were  inclined  to  regard 
the  fungus  as  only  an  incidental,  or  at  least  a  secondary,  factor' 
in  the  root  rot  of  the  tobacco,  especially  of  that  in  the  fields. 
After  an  extended  study  of  the  subject  the  writer  has  no  doubt 
of  the  parasitic  nature  of  the  fungus  under  certain  conditions 
and  believes  that  it  was  directly  responsible  for  the  serious 
injury  in  the  seed  beds  this  year.  Whether  or  not  the  very 
conspicuous  trouble  in  certain  of  the  tobacco  fields  of  Suffield 
was  primarily  and  chiefly  due  to  it  is  not  so  easily  settled  in 
our  mind,  though  there  is  no  doubt  that  it  was  at  least  partly 
responsible.  In  any  case  the  development  of  the  fungus  and 
the  consequent  injury  to  its  hosts  depends  largely  on  certain 
environmental  conditions  (nature  of  soil,  moisture,  etc.)  which 
will  be  discussed  later. 

Hosts  and  distribution.  In  order  to  determine  how  common 
this  fungus  is  and  how  large  a  number  of  plants  it  has  for 
hosts,  the  writer  made  a  rather  careful  examination  of  the  litera- 
ture of  the  subject  and  also  sent  inquiries  to  a  number  of  men 
who  would  be  most  likely  to  know  of  its  presence  in  the  various 
-tobacco  districts  in  the  United  States,  Cuba  and  Porto  Rico. 
As  a  result  of  this  search  no  one  was  found  who  had  observed 
the  fungus  (based  on  microscopic  examination)  on  tobacco 
plants  in  Cuba,  Porto  Rico,  Kentucky,  North  Carolina,  South 
Carolina,  West  Virginia,  Pennsylvania,  Tennessee,  Florida, 
Texas  or  Wisconsin.  This  does  not  mean  necessarily  that  the 
disease  does  not  exist  in  any  of  those  states  but  simply  that  no 
reliable  information  is  yet  at  hand  for  stating  positively  that  it 
does.  So  far,  then,  the  fungus  has  been  found  on  tobacco 
only  in  Italy,  Ohio  and  Connecticut,  but  we  have  reason  to 


ROOT    ROT   OF   TOBACCO.  345 

believe  that  it  also  occurs  in  Massachusetts  and  possibly  in 
South  Carolina.  If  it  occurs  in  Cuba,  the  experiment  station 
there,  at  least,  is  entirely  ignorant  of  its  presence. 

All  of  the  hosts  and  localities,  with  the  authorities  for  the 
same,  so  far  noted,  are  as  follows :  Aralia  quin  que  folia',  Gin- 
seng, Ohio  (Selby)  ;  Begonia  rubra,  Ohio  (Selby)  ;  Begonia 
sp.,  Germany  (Aderhold)  ;  Cochlearia  Armoracia,  horseradish, 
Kazan,  Russia  (Sorokin)  ;  Cyclamen  sp.,  Germany  (Sorauer)  ; 
Lupiniis  albus,  Halle,  Germany  (Zopf)  ;  Lupinus  angusti- 
folius,  Halle,  Germany  (Zopf)  ;  Lupinus  luteiis,  Halle,  Ger- 
many (Zopf)  ;  Lupinus  thermis,  Halle,  Germany  (Zopf)  ; 
Nemophila  auriculata,  King's  Clifife,  England  (Berkeley  & 
Broome)  ;  Nicotiana  Tahacum,  tobacco,  Italy  (Peglion,  Cap- 
pelluti- Alto  mare),  Ohio  (Selby),  Conn.  (Shamel,  Clinton)  ; 
Onohrychis  Crista-galli,  Halle,  Germany  (Zopf)  ;  Pisum  sati- 
vum, pea.  King's  Cliffe,  England  (Berkeley  &  Broome),  Halle, 
Germany  (Zopf),  Gembloux,  Belgium  (Marchal)  ;  Senecio 
elegans,  Berlin,  Germany  (Zopf)  ;  Trigonella  caerulea,  Halle, 
Germany  (Zopf)  ;    Viola  odorata.  Conn.  (Thaxter). 

Besides  the  above  host  Aderhold,  by  means  of  artificial 
inoculations,  infected  Scorzonera  hispanica,  Dauciis  Carota, 
Beta  vulgaris  and  Apium  graveolens  slightly  and  Phaseolus 
vulgaris  more  prominently.  There  is  also  some  indication  that 
the  fungus  attacks  somewhat  some  of  the  weeds  in  the  tobacco 
beds  in  Connecticut.  These  references  show  that  the  fungus 
has  a  wide  range  of  hosts,  which  are  widely  scattered  among 
the  different  families  of  flowering  plants,  but  that,  so  far  as 
reported,  those  of  the  leguminose  family  are  most  generally 
attacked. 

Structure  of  the  fungus.  The  mycelium  or  vegetative  part 
of  the  fungus  consists  of  hyaline,  septate,  branched  threads 
that  penetrate  into  the  tissues  of  the  root  eventually  causing 
their  death.  The  mycelial  threads  are  of  rather  narrow  diame- 
ter, chiefly  3  or  4'^/  and  their  branches  are  usually  formed 
near  the  apex  of  a  cell,  the  branch  being  cut  off  by  a  septum 
at  its  base,  as  shown  in  Fig.  14,  a.  The  mycelium  developed 
externally  on  the  hosts  soon  becomes  slightly  tinted  and  even- 
tually gives  rise  to  three  kinds  of  spores,  or  reproductive 
bodies.  Zopf  (22)  in  his  original  article  described  a  fourth 
kind  of  spores   (stylospores  or  spermatia  in  pyenidia),  but  as 


346        CONlSfECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

he  did  not  mention  these  in  his  later  article,  and  as  others  have 
not  described  them,  it  may  be  that  he  was  mistaken  about  their 
being  connected  with  this  fungus.  The  writer,  at  least,  has 
not  seen  them,  but  all  of  the  other  kinds  were  found  on  the 
diseased  tobacco  roots. 

The  first  kind  of  spores  formed  are  called  endospores,  Fig. 
14,  c,  because  they  are  formed  inside  a  special  thread  of  the 
mycelium.     This  special  endospore  case  is  formed  terminally  on 


Fig.  14.  a,  mycelium  (a\  fertile);  b,  endosporous  threads;  c,  endo- 
spores (c\  germinating)  ;  d,  chlamydospores  (d^  fragmenting,  d^, 
germinating)  ;    e,  ascospores. 

the  thread  or  on  terminal,  somewhat  clustered  branches.  It  has 
a  slightly  swollen  base,  usually  with  several  short  basal  cells,  and 
a  long  tapering  terminal  cell.  The  endospores  are  gradually 
formed  in  the  apex  of  this  terminal  cell  in  a  basipetal  manner 
and  are  pushed  out  of  the  ruptured  end  by  the  growth  of  the 
unfragmented  protoplasm  of  the  base.  Usually  these  fertile 
threads  are  slightly  tinted  but  have  very  thin  walls,  so  that  it  is 


ROOT    ROT   OF    TOBACCO.  347 

often  necessary  to  use  the  highest  powers  of  the  microscope  to 
determine  that  the  spores  originate  internally  in  the  thread  and 
not  by  its  direct  septation.  Often  one,  can  see  endospores 
slightly  protruding  beyond  the  case  and  in  old  specimens 
examples  are  found  where  the  case  projects  beyond  the  terminal 
endospores  as  shown  in  Fig.  14.  In  nutrient  cultures  very 
often  these  endospores  remain  attached  in  long  strings  after 
being  pushed  out  of  the  case.  The  endospores  are  hyalin,  thin 
walled,  oblong  to  linear,  and  vary  in  size  from  10  to  25 /x,  in 
length  by  4  or  5/x,  in  width.  They  have  a  conspicuous  nuclear- 
like  body  in  either  end.  Aderhold  does  not  consider  the  endo- 
spores as  sporangial  spores  but  rather  as  conidia. 

The  second  kind  of  spores  formed  are  the  chlamydospores, 
Fig.  14,  d,  which  are  thicker  walled,  dark  reddish  brown  bodies. 
They  rarel)^  germinate  soon  after  formation  and  so  are  in  the 
nature  of  resting  spores  and  are  adapted  for  carrying  the  fungus 
over  periods  unfavorable  for  growth.  They  are  borne  on  the 
same  mycelium  as  the  endospores,  often  as  side  branches  at  the 
base  of  an  endospore  thread.  Some  writers  have  considered 
them  as  simple  spores  adhering  in  chains,  but  they  are  more  prop- 
erly considered  as  compound  spores  consisting  of  one  or  two, 
rarely  three,  sterile  basal  cells  and  one  to  seven  fertile  cells. 
The  basal  cells  are  hyaline  or  slightly  tinted,  while  the  fertile  cells 
are  dark  reddish  brown,  thicker  walled  and  eventually  separate 
into  pill-box  shaped  individual  cells.  As  a  whole  the  compound 
spores  are  oblong  with  'the  terminal  fertile  cell  rounded  and 
sterile  basal  cells  tapering  slightly  toward  the  base.  The  length 
of  the  spores,  excluding  the  sterile  base,  varies  from  20  to  50^ 
and  their  width  from  10  to  iSh-.  While  these  spores  are 
usually  formed  on  the  mycelium  externally  on  the  root,  they 
are  sometimes  produced  sparingly  inside  the  cells  of  the  root. 
In  this  case  they  resemble  the  Torula  fungus,  hence  Berkeley's 
classification. 

The  third  kind  of  spores  are  the  ascospores,  Fig.  14,  e.  These 
are  dark  colored,  single  celled,  lenticular  spores  about  12^  in 
length  by  5)11  in  width.  They  are  produced  in  asci,  or  hyaline 
sacs,  each  ascus  containing  eight  ascospores  and  in  turn  these 
asci  are  enclosed  in  a  special  spherical  receptacle  called  the  peri- 
thecium.  While  we  have  found  these  ascospores  common  on 
the   older   tobacco    roots,    especially    toward   the    end    of   the 


34^         CONNECTICUT    EXPERIMENT    STATION    REPORT,     I906. 

season,  they  were  always  shed  out  on  the  tissues,  which  indi- 
cated that  the  asci  and  perithecia  were  either  very  fragile  or 
temporary.  So  far  as  our  own  observations  go  we  could  not 
positively  assert  their  relationship  to  the  other  spore  forms  of 
the  root  rot  fungus,  but  from  their  presence  and  the  observa- 
tions of  others  there  seems  to  be  no  reason  for  doubting  this 
relationship.  Though  the  fungus  develops  under  ground  it  is 
well  provided  with  means  for  its  propagation  and  dispersal 
through  these  various  spore  forms. 

Artificial  cultiires.  Aderhold  was  apparently  the  first  to 
make  pure  cultures  of  the  fungus  on  various  sterilized  media. 
The  writer  has  also  obtained  cultures  from  diseased  tobacco 
roots.  At  first  some  difficulty  was  experienced  in  getting  any 
growth  of  the  fungus,  either  because  the  spores  did  not  ger- 
minate or  because  this  fungus  was  easily  crowded  out  by 
bacteria  and  other  fungi.  Finally,  however,  several  isolated 
colonies  (possibly  from  endospores)  appeared  in  a  Petrie  dish 
separation  culture  of  acid  potato  agar  in  which  spores  from  a 
freshly  diseased  tobacco  root  had  been  used.  From  these,  pure 
cultures  in  test  tubes  were  easily  obtained.  The  fungus  grows 
very  readily  on  potato  agar  and  soon  produces  an  abundance  of- 
its  endospores  and  later  of  the  chlamydospores.  It  forms  a 
slight  aerial  growth  that  at  first  is  greyish  but  with  the  produc- 
tion of  chlamydospores  the  cultures  finally  become  quite  dark 
colored.  So  far  the  ascosporous  stage  has  not  appeared  in  the 
cultures;  but,  as  very  often  such  stages  do  not  appear  in  cul- 
tures, this  is  no  real  proof  that  it  is  not  a  stage  of  the  fungus  as 
declared  by  Zopf. 

These  artificial  cultures  give  very  favorable  opportunity  for 
studying  the  fungus  in  detail  and  for  determining  points  in  its 
life  history  not  easily  made  out  otherwise.  For  example,  the 
writer  has  only  occasionally  seen  the  endosporous  stage  on  the 
roots  of  tobacco  and  it  might  easily  be  entirely  overlooked.  In 
the  cultures,  however,  this  stage  is  the  first  to  appear  and 
produces  the  endospores  in  great  abundance  on  the  surface  of 
the  agar,  while  the  chlamydospores  are  produced  chiefly 
imbedded  in  the  agar,  to  which  it  gives  a  blackish  color  in  time. 
The  endospores  germinate  readily  in  drop  cultures  of  potato 
agar  and  manure-water  but  usually  fail  entirely  to  germinate 
in  pure  water.  The  fungus  also  grows  readily  on  sterilized 
horse  dung.     These  facts  seem  to  indicate  that  the  endospores 


ROOT    ROT    OF    TOBACCO.  349 

are  aerial  spores  and  would  develope  abundantly  in  manure 
piles,  thus  greatly  facilitating  the  spread  of  the  fungus.  Sev- 
eral writers  have  spoken  of  finding  a  whitish  growth  (appar- 
ently an  aerial  growth  of  the  endosporous  stage)  at  the  crown 
of  infected  plants,  but  so  far  on  tobacco  we  have  seen  no  such 
growth  but  have  found  chiefly  the  chlamydospores  forming  a 
blackish  growth  occasionally  at  the  crown  but  chiefly  on  the 
roots  or  rootlets  anywhere  under  ground.  As  the  fungus  is 
still  under  investigation  further  details  of  its  structure  and  life 
history  will  not  be  given  here. 

Synononiy  and  relationships.  As  has  been  stated,  Berkeley 
and  Broome  first  described  this  fungus,  placing  it  under  the 
genus  Torula  because  of  the  Torula-like  character  of  the 
chlamydospores,  which  were  the  only  fruiting  stage  observed 
by  them.  Zopf  was  the  first  to  recognize  the  endosporous  and 
the  ascosporous  stages  and  because  of  the  latter  he  placed  it  in 
a  new  genus  which  he  called  Thielavia.  This  same  year,  1876, 
Sorokin  (18),  of  Russia,  found  the  chlamydospores  on  the 
roots  of  horseradish  and,  thinking  the  fungus  to  be  a  new  spe- 
cies, called  it  Helminthosporium  fragile.  Sorauer  (16),  in 
1886,  apparently,  was  the  first  to  recognize  Sorokin's  species  to 
be  the  same  as  Berkeley's,  for  this  same  year  Saccardo  (11) 
ignored  their  identity  by  placing  Sorokin's  species  under  a 
different  genus,  Clasterosporium.  The  correct  name  of  the 
fungus  and  its  synonomy,  so  far  as  now  known,  is  as  follows : 

THIELAVIA  BASICOLA  (B.  &  Br.)  Zopf.     Sitz.  Bot.  Ver. 
Prov.  Brandenb.  18;    101-5.    Je.  1876. 
Torula  basicola  B.  &  Br.     Ann.  Mag.  Nat.  Hist.,  II,  5:  461. 

1850. 
Helminthosporium    fragile    Sor.      Hedw.    15:    113.      Au. 

1876. 

Clasterosporium  fragile   Sacc.     Sacc.   Syll.   Fung  4:  386. 

1886. 

Winter   (21),  Zopf   (24)   and  Saccardo   (10)   all  placed  the 

genus   Thielavia   under  the   family   Perisporieae   of   the   Peri- 

sporiaceae  (the  latter  also  including  the  family  Erysipheae,  the 

powdery    mildews)  ;     but    Fisher    (4)    did    not    consider    the 

genus  at  all  related  to  the  powdery  mildews,  as  he  placed  it  in 

the  family  Aspergillaceae  of  the  Plectascineae.     All  the  writers, 


35°        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

however,  consider  Thielavia  nearly  related  to  the  genera 
Penicillium  and  Aspergillus,  or  the  common  blue  molds.  So 
far  only  two  other  species  of  Thielavia  have  been  reported  and 
in  both  of  these  only  the  ascosporous  stage  is  described  by 
Saccardo.  Thielaviopsis  is  a  possibly  related  genus,  though 
no  ascosporous  stage  is  known,  as  one  of  its,  conidial  stages  is 
very  similar  to  the  endosporous  stage  of  Thielavia  hasicola. 

DETAILED    CONSIDERATION    OF   THE   TROUBLE    IN    CONNECTICUT. 

In  the  seed  beds. 

Difference  between  dampening  off  and  root  rot.  For  years 
the  tobacco  seed  beds  of  Connecticut  have  been  injured  more 
or  less  by  dampening  off  fungi.  These  dampening  off  troubles 
however,  are  quite  distinct  from  the  root  rot  disease.  With 
the  former,  the  stems  of  the  young  plants  are  attacked  above 
ground  by  certain  fungi  which,  when  soil  and  air  are  very 
moist,  may  develop  on  the  surface  of  the  beds  and  on  the  base 
of  the  plants  as  delicate,  whitish,  cobweb-like  growths.  These 
filaments  of  the  fungus  penetrate  into  the  tissues  of  the  stem 
and  induce  a  soft  rot  of  the  tissues  which  causes  the  plants  to 
collapse  and  a  further  rot  of  the  leaves  takes  place,  especially 
if  in  contact  with  the  ground.  Thus  vacant  spots  appear  in 
the  beds  where  all  the  plants  have  been  rotted  out;  or,  when 
the  trouble  is  not  so  bad  the  stand  is  thinned  by  the  deatli  of 
a  few  individuals.  Frequently  a  plant  may  be  attacked,  but, 
through  rapid  growth  or  moisture  conditions  unfavorable  for 
the  development  of  the  fungus,  escape  injury  further  than  a 
cankered  area  on  the  stem.  These  dampening  off  troubles  are 
augmented  by  very  damp  and  cloudy  spring  weather,  and  not 
infrequently  are  started  by  lack  of  skill  or  care  in  watering  or 
ventilating  the  beds.  As  the  fungi  are  capable  of  living  in  the 
vegetable  mold  of  the  soil,  they  become  established  in  the  beds 
and  cause  more  or  less  injury  each  year. 

Characteristics  of  root  rot.  The  root  rot  fungus,  on  the 
other  hand,  develops  almost  entirely  underground,  attacking  the 
roots  and  underground  part  of  the  stem.  The  tap  root,  which 
is  prominent  in  the  young  plants,  is  often  rotted  off  close  to 
the  stem  or  there  may  be  a  general  rotting  of  the  tap  and 
secondary  roots,  as  shown  in  Plate  XXIX.     Not  infrequently 


ROOT    ROT   OF    TOBACCO.  351 

severely  injured  plants  form  new  secondary  roots  further  up 
on  the  stem  and  under  favorable  conditions  partly  or  entirely 
outgrow  the  trouble.  Sometimes  the  roots  are  only  slightly 
injured,  having  the  secondary  roots  rotted  off  near  their  ends 
or  tliere  are  scattered  diseased  spots  that  may  be  finally  out- 
grown, as  the  fungus  does  not  develop  so  readily  on  the  larger 
and  harder  roots.  All  of  this  injury,  except  rarely  a  cankered 
spot  on  the  base  of  the  stem,  is  hidden  from  view  until  the  plants 
are  pulled  up.  When  this  is  done  one  is  often  surprised  to 
find  how  easily  the  plants  separate  from  the  soil,  but  an  exami- 
nation shows  that  there  were  few  or  no  roots  to  hold  the  plants 
to  it. 

The  grower  usually  first  notices  the  trouble  by  the  plants 
failing  to  make  normal  growth  or  coming  entirely  to  a  stand- 
still. The  leaves  may  show  to  his  critical  eye  an  unhealthy 
dark  green  color  which  he  often  describes  as  "black."  In  time 
there  is  a  very  uneven  stand  of  the  plants  in  the  bed  due  to 
some  plants  being  more  injured  than  others.  Eventually  there 
may  be  a  sickly  yellowing  of  the  older  leaves.  While  some 
of  the  plants  are  killed  when  quite  young  and  others  may  be 
carried  off  later,  still  it  is  very  remarkable  how  many  of  the 
plants  continue  to  live  even  when  most  of  their  roots  have  been 
rotted  off.  On  a  bright  day  this  lack  of  root  system  becomes 
evident  through  the  premature  wilting  of  the  plants.  Later  in 
the  season  the  beds  may  show  considerable  improvement,  since 
the  plants  have  had  time  to  develop  new  roots  and  the  warmer, 
drier  weather  is  more  favorable  for  their  outgrowing  the 
disease. 

Extent  of  the  trouble.  In  order  to  determine  how  general 
the  trouble  was  in  the  seed  beds  of  the  state,  the  writer,  by 
visits,  personal  inquiry  and  correspondence,  attempted  to  locate 
as  many  of  the  infested  beds  as  possible.  Such  beds  were  seen 
at  Simsbury,  Granby,  Tariffville,  Poquonock,  Hockanum  and 
Portland.  In  all,  however,  the  disease  was  definitely  located  in 
the  beds  of  less  than  twenty  growers.  Often  only  one  of  the 
beds  of  the  grower  was  seriously  injured.  No  doubt  this  does 
not  show  the  complete  distribution  of  the  trouble,  as  some 
growers  are  reticent  about  giving  information  concerning  such 
diseases.  Others  may  have  suffered  but  slightly  from  the 
trouble  and  so  it  would  easily  escape  their  notice ;    still  others 


352         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

may  have  suffered  in  ignorance  of  its  real  nature,  as  some 
growers  at  first  were  inclined  to  lay  the  trouble  to  fertilizer 
burn.  All  of  these  infected  beds  were  in  the  Connecticut 
valley,  the  chief  tobacco  region  of  the  state.  Although  similar 
effort  was  made  to  find  the  trouble  in  the  smaller  tobacco  region 
of  the  Housatonic  valley,  not  a  single  case  was  found  or  even 
heard  of  in  this  region. 

Loss  caused.  The  disease  at  its  worst  practically  ruined 
the  beds,  as  few  of  the  growers  would  risk  planting  from  such 
beds.  This  meant  the  loss  of  time,  etc.,  in  taking  care  of  the 
bed,  often  the  purchase  elsewhere  of  healthy  plants  and  fre- 
quently a  delay  in  setting  out  the  fields.  One  grower  esti- 
mated that  this  loss  to  him  was  equal  to  one  hundred  dollars. 
In  other  cases  growers,  who  set  from  beds  that  did  not  show 
the  trouble  badly,  became  scared  afterwards  because  the  plants 
did  not  start  promptly,  and  they  plowed  these  up  and  reset 
with  plants  from  uninfected  beds. 

Experiments  tried,  (i)  Sprinkling  seedlings.  Mr.  Shamel, 
in  the  article  in  the  Hartford  Courant,  was  reported  as  strongly 
recommending  "that  upon  the  first  appearance  of  the  pest  the 
remaining  plants  in  the  beds  must  be  sterilized  with  a  solution 
of  formaldehyde,"  of  a  strength  of  i  to  2000  of  water.  He 
recommended  sprinkling  the  affected  beds  once  a  week  with 
the  formalin,  thoroughly  soaking  the  plants  and  the  soil.  Mr. 
Shamel  based  this  recommendation  on  some  beds  he  had 
sprinkled  with  formalin  where  the  treated  plants  afterward 
seemed  to  make  a  better  growth  than  those  not  sprinkled.  In 
view  of  this  recommendation  the  writer  had  treated  a  part  of  a 
bed  badly  infected  with  the  root  rot  at  Portland.  This  bed  was 
first  treated  June  nth  with  formalin  of  a  strength  about  i  to 
1500.  A  very  thorough  sprinkling  was  given  the  plants,  using 
at  the  rate  of  a  gallon  to  each  six  square  feet  of  the  bed. 
Altogether  the  plants  were  sprinkled  with  the  formalin  five 
times,  June  nth,  13th,  15th,  19th  and  25th.  The  plants  were 
finally  examined  July  loth  by  the  writer,  and  the  treated  plants 
did  not  seem  to  be  any  better,  more  vigorous,  or  freer  from  root 
rot  than  those  side  by  side  that  were  not  treated ;  neither  had 
the  owner  noticed  at  any  time  any  indication  of  a  better  growth 
in  the  treated  part  of  the  bed. 


ROOT    ROT    OF    TOBACCO.  353 

We  also  had  the  opportunity  to  examine  several  beds  at 
Hockanum  and  Simsbury  that  were  sprinkled  two  to  several 
times  under  Mr.  Shamel's  direction,  but  in  no  case  were  we 
able  j;o  find  any  positive  evidence  that  the  sprinkling  had  been 
of  value  in  checking  the  root  rot  or  hastening  a  healthy,  growth 
of  the  diseased  plants ;  and  two  out  of  the  three  growers  who 
had  tried  the  experiment  reported  unfavorably  for  the  treat- 
ment. One  of  the  growers,  however,  thought  that  the  treat- 
ment had  been  of  benefit  to  his  beds,  but  in  this  case,  so  far  as 
the  writer  could  determine,  this  benefit,  if  any,  was  not  in 
preventing  the  root  rot,  but  rather  in  lessening  dampening  off 
of  the  plants,  which  is  another  disease  altogether. 

From  the  theoretical  side  this  treatment  does  not  seem  to 
promise  much,  since  the  formalin  must  be  used  in  very  weak 
solution,  so  as  not  to  injure  the  foliage  or  roots  when  sprinkled 
on  the  plants.  It  is  quite  possible  that  this  weak  formalin  might 
act  unfavorably  on  the  very  thin-walled  endospores  of  the 
fungus,  but  on  the  thick-walled  chlamydospores,  which  are  the 
common  spores  on  the  roots,  it  is  doubtful  if  such  a  weak 
solution  would  have  as  injurious  an  action  as  it  would  on  the 
tender  root  hairs  of  the  tobacco.  Then,  too,  the  mycelium  of 
the  fungus  on  the  diseased  roots  is  largely  within  their  tissues, 
and  certainly  this  would  not  be  killed  without  killing  the  roots 
themselves. 

Taking  all  the  evidence  into  consideration,  we  do  not  believe 
that  sprinkling  beds  already  showing  the  disease  will  be  of 
value  in  lessening  injury  from  root  rot,  and  -we  doubt  if  such 
treatment  will  be  of  any  considerable  value  even  if  it  is  begun 
before  the  appearance  of  the  rot.  Now,  in  this  statement,  we 
do  not  include  the  dampening  off  and  stem  rot  troubles,  since 
in  some  of  the  beds  having  these  troubles  there  did  seem  to  be 
some  benefit  derived  from  the  treatment.  In  these  cases,  how- 
ever, the  sterile  threads  of  the  fungus  creep  exposed  over  the 
surface  of  the  ground  and  on  the  plants,  and  considerable 
moisture  is  necessary  for  their  development.  If,  then,  in  place 
of  the  ordinary  water,  the  weak  formalin  is  used,  while  it  might 
not  kill  the  fungus  threads,  it  certainly  would  not  be  so  favora- 
ble for  their  further  development.  This  phase  of  the  subject  is 
discussed  under  the  Stem  Rot  of  Tobacco,  page  327  of  this 
report. 

25 


354         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

(2)  Sterilizing  the  soil.  While  the  sprinkling  method  does 
not  appear  to  the  writer  to  have  much  value,  the  use  of  stronger 
formalin  on  the  soil,  as  a  disinfectant,  before  the  beds  are 
seeded  down  did  seem  to  be  of  value  in  killing  out  the  root  rot 
fungus,  and  so  exempting  the  seedlings  from  its  attack.  Selby 
of  Ohio  has  already  obtained  encouraging  results  against  other 
soil  fungi  by  such  treatment.  To  test  this  in  a  preliminary  way, 
soil  from  an  infected  bed  was  obtained  and  placed  in  boxes  in  the 
greenhouse.  On  June  23d,  the  soil  of  box  i  was  thoroughly 
soaked  with  formalin  of  a  strength  of  i  to  100  of  water ;  the  sec- 
ond, with  formalin  of  a  strength  of  i  to  200,  and  the  third,  or 
check,  merely  soaked  with  a  similar  amount  of  water.  After 
covering  for  a  day  to  keep  in  the  fumes,  the  soil  was  stirred  and 
aired  for  a  week  to  allow  the  formalin  to  escape.  The  boxes 
were  then  seeded  with  tobacco,  and  afterward  treated  alike 
"throughout  the  test.  Root  rot  did  not  develop  as  badly  in  any  of 
these  boxes  as  it  had  earlier  in  the  seed  bed  from  which  the  soil 
was  taken.  It  did  appear  in  time  somewhat  prominently  in  the 
untreated  box.  There  was  also  some  in  the  box  treated  with 
the  weaker  strength  (i  to  200)  of  formalin,  thus  indicating  that 
this  treatment  was  not  quite  strong  enough  for  practical  use. 
In  the  box  treated  i  to  100,  while  there  was  a  very  slight  trace 
of  the  rot,  the  treatment  practically  prevented  it.  -In  neither 
of  the  treated  boxes  did  the  formalin  seem  to  retard  germina- 
tion, or  injure  the  plants  afterwards,  but  instead,  these  boxes 
really  gave  a  thicker  stand  of  plants. 

From  the  preceding  experiment  it  seemed  probable  that 
thorough  treatment  of  an  infected  bed  with  formalin  of  the 
strength  of  i  to  100  might  prove  very  useful  in  preventing 
the  root  rot.  Consequently  part  of  a  badly  infected  bed  at 
Portland  was  treated  on  July  loth.  A  thorough  soaking 
was  given,  using  a  gallon  to  every  i>^  square  feet.  The 
treated  part  was  covered  with  sash  for  a  couple  of  days  to 
hold  in  the  fumes,  and  then  aired  for  about  a  week  before  seed- 
ing it  and  the  adjacent  untreated  strip,  which  was  to  constitute 
the  check.  The  illustration,  Plate  XXX,  a,  shows  the  condition 
of  the  treated  and  untreated  plots  of  this  bed  on  September 
5th.  As  is  seen  from  this,  plants  in  the  treated  part  were 
much  larger,  being  large  enough  for  setting  out,  and  there  was 
a  thicker  and  more  uniform  stand.     There  was  no  indication  of 


ROOT    ROT    OF    TOBACCO.  355 

disease  to  the  naked  eye.  A  microscopic  examination  of  the 
roots  showed  only  traces  of  the  root  rot  fungus.  The  untreated 
plants,  on  the  other  hand,  revealed  some  external  signs  of  the 
trouble,  by  the  dwarfed,  darker  colored  foliage,  and  an  examina- 
tion of  the  roots  showed  the  fungus  present  on  all  of  the  plants, 
in  some  cases  rotting  the  roots  badly.  A  later  examination,  on 
September  24th,  still  showed  the  plants  in  the  treated  soil 
superior  to  those  in  the  untreated ;  and  the  owner  stated  that 
the  difference  in  weeding  the  beds  had  been  greatly  in  favor  of 
the  treated  part,  which  indicated  that  the  treatment  had  been 
strong  enough  to  kill  many  of  the  weed  seeds.  The  only  thing 
that  prevents  the  conclusion  that  this  evident  difference  between 
the  treated  and  untreated  plants  was  entirely  due  to  the  treat- 
ment is  the  fact  that  the  untreated  part  of  the  bed  was  not 
soaked  down  at  the  time  of  treatment  with  an  equal  amount  of 
water.  It  is  barely  possible  that  the  thorough  soaking  the 
treated  part  received  was  in  itself  a  favorable  condition  for 
better  plants  during  the  month  of  July.  This  month,  however, 
was  rather  moist,  and  after  seeding  the  treated  and  untreated 
parts  were  watered  alike,  apparently  as  often  as  needed.  Any 
great  amount  of  water  in  the  soil  in  the  untreated  part  would 
have  been  more  favorable  for  the  development  of  the  root  rot. 
Because  of  this  drier  condition  of  the  soil,  and  possibly  because 
of  other  seasonal  conditions,  as  heat,  the  root  rot  was  not  so 
bad  in  this  bed  as  in  the  spring.  Even  the  dwarfed  plants  had 
a  better  root  system,  as  shown  by  their  not  being  so  easily  pulled 
from  the  soil.  There  was  no  question,  however,  that  the  treat- 
ment was  at  least  partially  responsible  for  the  difference  in  the 
condition  of  the  plants. 

Based  on  the  above  experiment,  parts  of  two  other  seed 
beds  were  treated  in  the  fall  to  determine  the  ef^ciency 
of  this  treatment.  Another  was  treated  this  spring  to  deter- 
mine the  comparative  value  of  spring  and  fall  treatment. 
In  the  fall  treatments  a  very  thorough  soaking  with  formalin, 
I  to  100,  using  one  gallon  to  each  square  foot,  was  given.  It 
is  quite  possible  that  this  thorough  soaking  of  the  ground  in 
spring,  when  the  soil  is  naturally  moist,  will  not  always  allow 
it  to  dry  out  sufficiently  for  the  most  favorable  growth  of  the 
plants,  so  only  ^  of  a  gallon  per  square  foot  was  used.  The 
results  of  these  experiments  cannot  be  reported  until  later. 


356         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

Besides  the  sterilization  of  the  soil  with  formalin,  part  of 
a  bed  in  one  of  the  fall  treatments  was  sterilized  with  steam 
by  means  of  a  steam  rake,  whose  teeth  were  forced  into  the 
soil.  Of  course  the  comparative  merits  of  this  treatment  and 
the  formalin  treatment  are  not  yet  determined,  but  in  so  far  as 
cost  and  quickness  of  treatment  are  concerned,  the  formalin 
method  without  question  is  far  superior.  As  the  result  of  our 
various  experiments  and  observations,  later  in  this  article,  under 
Preventive  Measures,  we  recommend  certain  tentative  treat- 
ments for  the  prevention  of  the  root  rot. 

In  the  fields. 

Effect  on  the  plants.  Beside  the  backset  early  in  the  season, 
which  many  plants  entirely  or  largely  outgrew,  there  were  other 
cases  where  the  plants  made  no  satisfactory  growth  the  whole 
season.  Examination  of  the  roots  showed  that  the  fungus  had 
continued  its  injurious  action  here  during  the  season.  Such 
plants  usually  did  not  have  the  normal  main  and  fibrous  root 
system  shown  in  the  healthy  plant  in  Plate  XXXI,  b ;  but  the 
main  roots  were  more  or  less  rotted  off  or  easil}^  broken  when 
pulled  up  from  the  ground,  and  the  development  of  the  fibrous 
roots  and  rootlets  was  very  deficient  (Plate  XXXI,  b)  or  abnor- 
mally clustered  at  the  crown.  The  fungus  evidently  can  work 
on  the  young  rootlets  and  the  small  fibrous  roots  much  easier 
than  on  the  larger  and  more  woody  secondary  roots.  While  it 
sometimes  rotted  off  the  larger  roots,  it  more  frequently  showed 
as  an  encircling  banded  blackish  growth  that  was  apparently 
doing  comparatively  little  injury.  These  blackish  growths 
(Plate  XXXI,  a),  in  the  examination  of  the  washed  roots, 
gave  a  very  good  idea  of  the  abundance  of  the  fungus  and  its 
probable  injury  to  the  plant.  So  far  as  was  learned,  the  fungus 
did  not  attack  any  part  of  the  plant  above  ground,  though  occa- 
sionally plants  with  black  sunken  areas  were  found  where  the 
trouble  may  have  had  its  start  from  a  root  rot  injury. 

Extent  of  the  trouble.  In  order  to  determine  how  general 
the  fungus  was  in  the  fields,  the  writer  made  a  careful  exami- 
nation of  forty-six  different  fields  scattered  over  the  state. 
These  were  examined  chiefly  after  the  tobacco  had  been  cut  in 
the  fall.     The  roots  of  at  least  ten  plants  in  different  parts  of 


ROOT    ROT   OF   TOBACCO.  357 

each  field  were  pulled  up  and  washed  and  then  examined  for 
the  characteristic  black  spots  of  the  fungus.  These  tests  were 
verified  later  by  a  microscopic  examination.  Twenty-eight  of 
these  fields  were  in  seven  different  towns  in  the  tobacco  region 
of  the  Connecticut  valley.  In  all  of  these  fields,  except  two, 
the  fungus  was  present,  at  least  to  some  extent  on  the  roots, 
thus  showing  it  to  be  quite  general  in  its  distribution  in  this 
valley.  In  two  towns  in  the  Housatonic  valley  eighteen  fields 
were  examined,  but  the  fungus  was  found  only  in  eight  of 
these. 

Damage  done.  In  none  of  the  fields  in  the  Housatonic 
valley  was  the  fungus  found  in  any  abundance,  and  in  most 
of  the  eight  cases  only  a  trace  of  it  was  seen  on  a  few  of  the 
roots.  Neither  was  there  complaint  by  the  growers  of  any 
trouble  that  could  at  all  be  attributed  to  this  fungus.  So  it  can 
be  pretty  safely  stated  that  in  this  valley  there  was  no  injury 
this  season  from  the  root  rot.  In  at  least  eleven  of  the  twenty- 
eight  fields  in  the  Connecticut  valley  the  fungus  was  found 
abundant  enough  on  the  plants  examined  to  have  caused  appre- 
ciable injury.  In  all  of  these  cases  conversation  with  the 
owners  showed  that  the  field  as  a  whole  or  in  spots  had  not 
done  as  well  as  it  should  have  done.  In  some  cases  it  was 
merely  a  small  spot  or  portion  of  the  field  that  did  not  give  a 
normal  growth,  and  an  examination  of  the  roots  from  these 
places  always  showed  more  serious  injury  by  the  fungus  than 
in  the  rest  of  the  field.  Serious  damage  to  the  fields  as  a 
whole,  however,  was  confined  chiefly  to  the  region  of  Sufifield, 
and  here  the  root  rot  was  most  abundant.  In  this  town  a  num- 
ber of  the  fields  of  some  of  the  best  tobacco  growers  did 
unusually  poorly  in  a  year  when  the  crop  in  general  was 
unusually  good.  In  these  fields  the  tobacco  at  harvest  time  was 
smaller  than  it  should  have  been  and  on  certain  areas  made  no 
satisfactory  growth  through  the  season  and  so  was  practically 
worthless.  The  tobacco  from  these  poorest  spots  often  failed 
to  cure  down  properly  in  the  barns,  some  leaves  still  remaining 
green  late  in  October,  when  the  main  bulk  of  the  crop  in  the 
same  barn  was  ready  to  come  down.  As  some  of  the  most 
seriously  injured  fields  were  of  considerable  size,  this  short 
crop  meant  a  serious  loss  to  the  growers.     According  to  one 


'358         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

grower,  at  least,  the  quality  of  this  tobacco  was  not  seriously- 
affected. 

Secondary  factors  possibly  determining  the  injury  in  the 
fields.  Some  of  the  growers,  especially  with  the  seed  bed 
trouble,  were  inclined  at  first  to  look  upon  the  injury  as  a 
fertilizer  burn.  There  seems  to  be  little  ground  for  this  belief 
as  regards  the  seed  beds.  Whether  or  not  the  presence  of  more 
or  less  of  certain  of  the  fertilizers  used  would  stimulate  or 
retard  the  growth  of  the  fungus  is  another  question  not  so 
easily  answered.  It  is  not  definitely  known  whether  an  acid, 
alkaline  or  a  neutral  soil  is  best  adapted  to  the  growth  of  the 
fungus,  which  we  know  can  grow  in  the  soil  itself  apart  from 
the  tobacco  root,  but  it  is  reasonable  to  suppose  that  this  factor 
may  have  its  influence.  Neither  can  we  state  positively  v/hether 
or  not  certain  methods  of  field  fertilization  (showing  in  an 
excess  or  lack  of  certain  fertilizer  constituents  this  season) 
had  an  injurious  action  on  the  development  of  the  tobacco  aside 
from,  and  possibly  in  the  worst  fields  greater  than,  the  injury 
that  was  evidently  caused  by  the  root  rot  fungus.  One  of  the 
growers  whose  fields  suffered  severely  was  inclined  to  lay  it 
to  the  excessive  use  year  after  year  of  potash  fertilizers,  which 
gradually  accumulated  in  the  soil,  and  especially  to  the  use  of 
the  carbonate  of  potash.  Possibly  the  use  of  infected  manure 
may  have  had  a  bearing,  as  this  would  be  favorable  for  the 
development  of  the  fungus.  No  special  evidence,  however,  was' 
obtained  along  this  last  line  unless  it  was  in  the  case  of  one  of 
the  seed  beds. 

A  very  prominent  factor,  undoubtedly,  is  moisture.  One 
grower  stated  that  the  worst  infected  fields  in  Suffield  were 
those  that  had  been  under  tents  a  couple  of  years  previously. 
If  this  was  generally  true,  it  is  possible  that  the  more  moist 
condition  of  the  soil  when  under  the  tents  gave  the  fungus  a 
better  chance  to  develop  and  infect  those  fields  later.  A  very 
moist  soil  seems  to  be  most  favorable  for  the  development  of 
the  fungus,  as  the  lower  or  damper  spots  in  the  fields  usually 
showed  the  most  trouble.  The  nature  of  the  subsoil  as  regards 
drainage  also  may  have  had  its  bearing,  especially  early  in 
the  summer.  The  character  of  the  past  season  no  doubt  Avas 
also  an  important  factor.  The  cold  wet  weather  of  early  spring 
helped  along  the  trouble  in  the  seed  beds,  particularly  when 


ROOT    ROT   OF   TOBACCO.  359 

they  were  not  properly  ventilated.  The  rainfall*  in  June  and 
July  was  considerably  above  the  average,  which  was  no  doubt 
favorable  for  the  growth  of  the  fungus  in  the  fields  and  may 
have  had  its  bearing'  on  the  fertilizer  question. 

Future  injury?  The  questions  arise,  is  this  trouble  likely 
to  occur  as  seriously  in  the  worst  fields  another  year,  and  will 
it  grow  more  injurious  in  time  in  the  fields  where  it  is  at  pres- 
ent doing  little  or  no  damage?  It  is  not  possible  to  answer 
these  questions  definitely,  because  of  the  other  factors  than  the 
mere  presence  of  the  fungus  in  the  field  that  have  an  influence 
in  determining  the  injury  done.  Taking  all  of  these  factors 
into  consideration,  and  the  fact  that  the  trouble  appeared  so 
suddenly  and  prominently  this  year  when  no  doubt  the  fungus 
must  have  been  present  in  the  soil,  at  .least  inconspicuously,  for 
some  time  (as  it  now  is  in  some  parts  of  the  Housatonic  valley, 
with  no  injury  to  the  crop),  the  writer  is  inclined  to  believe  that 
it  is  not  certain  that  the  trouble  will  appear  next  year  and  there- 
after with  increasing  severity.  It  seems  most  probable,  aside 
from  a  certain  slight  injury  each  year,  that  the  character  of  the 
season  will  largely  determine  whether  or  not  serious  injury, 
like  that  of  the  present  year,  takes  place.  However,  it  is  very 
desirable  for  the  growers  to  be  well  informed  regarding  the 
nature  of  the  trouble  and  to  do  what  is  feasible  in  the  way  of 
preventive  measures. 

Experiments  tried  in  the  field.  A  number  of  observations 
were  made  and  a  few  experiments  tried  to  determine  the  exact 
nature  of  the  trouble  after  plants  had  been  set  out  in  the  field, 
for  it  was  very  soon  determined  that  the  fungus  was  present 
in  the  tobacco  fields  even  in  some  cases  where  the  growers  had 
not  noticed  it  in  their  beds.  In  these  experiments  and  obser- 
vations it  was  aimed  to  determine  three  things,  namely;  (i) 
Effect  of  transplanting  diseased  plants  in  the  fields,  (2)  Effect 
of  transplanting  healthy  plants  into  infected  soil,  (3)  Effect  of 
environment  on  the  development  of  the  disease.  We  will  dis- 
cuss these  points  briefly  in  the  following  paragraphs. 

(i)  Effect  of  transplanting  diseased  plants  in  the  field. 
Naturally  a  grower,  when  he  has  a  diseased  bed,  uses  only  the 


*  The  rainfall  at  New  Haven  for  June  was  over  5  inches,  giving  an 
excess  of  considerably  over  2  inches  when  compared  with  the  average 
for  thirty-four  years.     The  excess  for  July  was  .68  of  an  inch. 


360         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

best  plants  from  that  bed,  if  he  uses  them  at  all.  Some  growers 
used  plants  from  diseased  beds,  and  seeing  that  they  did  not 
start  promptly,  plowed  them  up.  In  one  case  at  Portland,  a 
grower  used  at  first  the  best  plants  from  his  diseased  bed,  and 
then  becoming  scared,  bought  the  remainder  of  his  plants. 
Those  used  from  his  own  bed  in  the  end  made  a  more  satis- 
factory crop  than  those  he  bought,  because  calico  developed 
badly  in  the  latter.  He  thought,  however,  that  the  plants  from 
the  diseased  bed  did  not  do  quite  as  well  as  plants  ordinarily 
did  on  the  land  in  which  they  were  planted.  Another  grower 
at  Bushy  Hill  used  plants  from  his  diseased  bed,  but  soon  after- 
ward plowed  them  all  up  except  one  row,  and  reset  with  plants 
from  a  healthy  bed.  At  first  the  plants  in  the  row  that  was 
left  did  not  seem  as  thrifty  as  the  healthy  plants  reset  later,  but 
at  the  end  of  the  season  they  did  not  appear  from  a  casual 
examination  to  be  much  different,  except  that  they  had  more 
calico.  In  this  same  field  one  of  the  United  States  Govern- 
ment experts  had  also  set  out  a  row  each  from  healthy  and 
diseased  beds.  When,  through  the  courtesy  of  the  grower,  the 
writer  examined  these  two  rows  at  the  end  of  the  season,  the 
difference  between  them,  if  any,  was  not  marked.  Likewise 
some  plants  from  diseased  beds  set  out  at  Tariffville  for  the 
same  purpose  did  not,  to  the  writer,  show  any  marked  injury. 
The  only  experiment  tried  by  the  writer  was  on  the  Experi- 
ment Station  grounds,  with  a  few  plants  obtained  from  diseased 
beds  at  Simsbury  and  Poquonock.  These  plants  were  set  out 
in  three  rows.  In  the  first  row  the  plants  were  entirely  too 
small  for  planting,  and  the  roots  were  very  badly  injured. 
Such  plants  were  used  because  they  were  the  worst  that  could 
be  obtained.  In  the  second  row  the  plants  were  in  fair  shape 
and  almost  large  enough  for  planting,  but  the  roots  were  rotted 
considerably.  In  the  third  row  the  plants  were  of  fair  size  and 
appearance,  showing  very  little  rot  on  the  roots,  and  were 
such  plants  as  a  grower  would  select  as  the  best  from  the  dis- 
eased beds.  The  plants  were  set  in  soil  free  from  the  fungus, 
and  on  a  cloudy  day,  and  were  watered  at  first ;  but  they  did  not 
have  any  special  fertilization  or  cultivation.  Unfortunately, 
soon  after  they  were  set  out,  a  heavy  rain  badly  washed  the 
soil  over  some  of  the  smallest  plants  in  the  first  row,  drowning 
out  a  few,  so  that  this  may  possibly  have  had  some  influence  on 


ROOT    ROT   OF   TOBACCO.  36 I 

their  later  growth.  At  the  end  of  the  season  this  test  showed 
the  following  facts:  (a)  That  very  few  plants  had  been  killed 
outright  by  the  root  rot.  (b)  That  at  first  those  with  badly 
diseased  roots  were  considerably  retarded  in  growth,  since  they 
had  to  form  new  roots,  (c)  That  some  of  the  badly  diseased 
plants  in  the  first  row  made  only  a  very  stunted  growth  during 
the  whole  season.  Everything  considered,  those  in  the  second 
row  made  a  very  fair  growth,  despite  the  fact  that  they  started 
with  considerable  rot  on  the  roots.  Those  of  the  third  row 
made  the  best  growth,  and  were  fair  plants,  (d)  The  final 
examination  of  the  roots  on  October  ist  showed  that  there  was 
then  very  little  evidence  of  rot  on  them,  even  on  the  most 
stunted  plants,  so  that  evidently  the  fungus  had  soon  been  out- 
grown ;  what  damage  it  had  caused  was  that  done  to  the  young 
plants,  from  which  injury  apparently  in  the  worst  cases  they 
had  never  recovered.  There  was  no  calico  on  any  of  the  plants. 
Plate  XXXII,  b,  shows  a  photograph  of  a  part  of  these  plants 
taken  on  October  ist,  those  in  the  foreground  being  in  the 
first  row. 

From  these  observations  and  experiments  we  may  reason- 
ably conclude  that  because  rot  appears  in  a  bed  it  does  not 
necessarily  mean  that  good  plants  taken  from  it  will  produce  a 
poor,  or  even  an  inferior,  crop.  That  badly  diseased  plants  will 
do  poorly,  especially  at  first,  there  seems  to  be  little  doubt.  That 
good  plants  showing  some  disease,  under  some  conditions  will 
do  worse  than  under  others,  also  seems  certain.  While  we  do 
not  advocate  the  use  of  plants  from  diseased  beds  if  others  can 
be  obtained,  we  do  think  that  it  is  possible  under  certain  con- 
ditions of  soil,  moisture,  etc.,  for  the  best  plants  from  these 
beds  to  do  as  well  as  plants  taken  from  a  bed  not  showing  the 
disease.  However,  the  grower  in  this  case  must  take  a  risk 
that  they  will  do  as  well. 

(2)  Effect  of  transplanting  perfectly  healthy  plants  in 
infected  soil.  As  the  disease  showed  in  some  fields  when  the 
plants  were  obtained  from  beds  supposed  to  be  free  from  the 
trouble,  there  is  question  whether  they  became  infected  in  the 
field.  If  this  were  true,  the  fungus  would  evidently  carry  over 
in  these  fields  from  season  to  season,  doing  more  or  less  damage 
as  conditions  were  favorable  or  unfavorable,  since  tobacco  is 
grown  on  the  same  land   year  after  year.     We  believe  that 


362        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

the  fungus  does  become  established  in  the  fields  in  this  way. 
That  perfectly  healthy  plants  of  the  age  for  setting  can  become 
infected  when  transplanted  in  infected  soil  is  shown  by  the 
following  experiment.  A  grower  at  Poquonock  had  a  bed  that 
showed  the  disease  prominently,  and  after  the  plants  were  taken 
from  this  bed  on  June  2d,  at  our  request  he  set  out  thirty-nine 
plants  in  it,  which  showed  absolutely  no  sign  of  the  disease  on 
their  roots.  On  July  20th,  see  Plate  XXXII,  a,  we  examined 
the  roots  of  a  third  of  these  plants,  and  found  more  or  less 
root  rot  on  all  of  them,  and  in  some  cases  enough  to  cause 
considerable  injury.  The  plants  were  quite  variable  in  size, 
and  not  as  thrifty  as  they  should  have  been,  but  this  in  part  was 
due  to  the  character  of  the  soil,  which  was  a  fine,  clay-loam 
that  easily  became  water-soaked.  Later  examination  showed 
the  disease  on  the  roots  of  all  the  plants.  I  have  no  doubt  that 
this  close,  wet  soil  was  favorable  for  the  development  of  the 
root  rot  fungus,  since  it  was  the  only  bed  at  this  place  of  this 
character,  and  the  only  one  in  which  the  root  rot  appeared. 

(3)  Effect  of  environment  on  development  of  the  disease. 
We  are  quite  convinced,  aside  from  the  presence  of  the  fungus 
in  the  soil,  that  the  character  of  the  season  (especially  the  mois- 
ture, and  possibly  unusually  cold,  wet  spring  weather)  and  the 
character  of  the  soil  and  subsoil  (fineness,  liability  to  become 
water-soaked,  drainage,  amount  of  humus,  especially  in  the 
shape  of  manure)  have  much  to  do  with  determining  whether 
or  not  the  fungus  does  much  damage.  We  have  tried  growing 
tobacco  in  soil  from  diseased  beds  and  fields  in  the  greenhouse 
later  in  the  season,  but  in  almost  all  of  these  experiments  the 
root  rot  has  not  been  as  bad  as  it  was  in  the  open  beds  and  the 
fields  presumably  because  the  environmental  conditions  were 
different.  A  fine  clay  soil  that  easily  water-soaks,  as  in  the  bed 
mentioned  previously,  seems  to  be  one  condition  favoring  the 
disease,  since  one  of  the  worst  fields  seen  has  a  soil  similar  to 
this.  In  another  case,  the  use  of  a  heavy  filling  of  manure 
beneath  the  seed  bed  for  artificial  heat,  coupled  with  careless 
watering  and  ventilating  at  a  critical  time,  gave  what  the  grower 
desired,  a  rapid  growth  of  the  plants,  but  also  admirable  condi- 
tions for  the  development  of  the  fungus,  which  soon  appeared. 
To  determine  the  action  of  fertilizers,  a  series  of  tests  in  dupli- 
cate were  started  late  in  the  fall  in  crocks  in  the  greenhouse. 


ROOT    ROT   OF   TOBACCO.  363 

with  soil  from  two  diseased  fields.  So  far  these  tests  do  not 
show  any  marked  difference  in  the  amount  of  rot  (which  is  now 
present  on  many  of  the  roots  but  not  doing  conspicuous  dam- 
age), due  to  using  carbonate  of  potash,  high-grade  sulphate  of 
potash,  slaked  lime,  acid  soil,  or  no  fertilizer  at  all.  There 
does  seem  to  be  more  of  the  fungus  in  the  crocks  where  manure 
was  used,  and  in  those  crocks  where  the  soil  was  treated  with 
formalin  there  is  no  rot  at  all.  The  experiment  of  course  is 
not  yet  completed,  but  so  far  it  does  not  substantiate  the  com- 
plaint made  by  ^ome  growers  against  injury  from  artificial 
fertilizers.  The  soil  was  taken  from  fields  of  a  grower  who 
beheved  that  the  excessive  use  of  potash  year  after  year  had 
been  responsible  for  the  injury.  In  these  greenhouse  tests 
450  pounds  per  acre  of  carbonate  of  potash  and  600  pounds  of 
high-grade  sulphate  of  potash  wera  used ;  but  as  the  experi- 
ment was  not  conducted  under  the  same  seasonal  or  field  condi- 
tions, this  might  make  some  difference  in  the  results. 

PREVENTIVE  MEASURES. 

Danger  of  infected  beds.  The  common  experience  of  the 
growers  whose  seed  beds  were  worst  infected  was  that  the 
trouble  had  appeared  in  them  last  year  to  a  limited  extent. 
This  seems  to  indicate  that  the  fungus,  like  most  other  soil 
fungi,  after  it  has  become  established  in  a  bed  will  do  more  or 
less  injury  each  year — though  no  doubt  the  season  and  the 
attention  given  the  bed  will  influence  its  development.  It 
seems  desirable,  therefore,  not  to  use  the  infected  seed  bpds 
again  for  some  time  when  new  ones  can  be  conveniently  made. 
Most  growers,  however,  are  reluctant  to  give  up  their  old  beds 
either  because  of  their  handy  location,  the  fine  condition  of  the 
soil  or  for  other  reasons.  In  these  cases  it  will  be  desirable  to 
use  some  form  of  sterilization  to  eradicate  the  fungus. 

Sterilisation  of  beds.  Sterilization  of  the  beds  is  helpful, 
not  only  in  preventing  or  lessening  injury  by  the  root  rot  and 
dampening  off  fungi,  but  it  also  destroys  more  or  less  of  the 
weed  seeds  and  insects.  Three  methods  have  been  used  with 
more  or  less  success  on  tobacco  and  other  seed  beds:  ist, 
Burning  dry  tobacco  stalks  or  other  fuel  on  the  beds  under  a 
metal  cover,  which  throws  the  heat  down  into  the  soil,  has  been 
tried  somewhat  in  this  state  for  destroying  weed  seeds.     It  is 


364        CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

said  to  be  quite  helpful  in  this  respect,  and  it  will  probably  also 
kill  the  soil  fungi,  near  the  surface  of  the  ground  at  least.  Too 
hot  a  fire,  however,  may  burn  out  the  humus  of  the  soil  or  make 
plant  food  less  soluble  and  so  do  as  much  harm  as  good.  2d, 
Sterilization  by  steam  has  been  profitably  employed  against 
soil  fungi  and  nematodes  in  greenhouses  and  hot  beds  for 
some  time,  and  is  now  used  in  a  few  cases  in  this  state  to  kill 
the  weeds  in  tobacco  beds.  There  is  no  reason  why  it  should 
not  be  as  successful  in  killing  the  root  rot  fungus  as  the  other 
soil  fungi.  There  is  on  the  market  a  steam  rake  whose  points 
when  forced  into  a  bed  carry  the  steam  into  the  soil  from  any 
attached  steam  boiler.  The  chief  objection  to  this  method  of 
sterilization  is  the  cost  of  the  apparatus  and  the  trouble  and 
time  taken  in  heating  the  beds.  3d,  Treating  the  soil  with  form- 
alin is  another  method  that  is  coming  into  use  for  combating 
soil  fungi.  Preliminary  tests  with  this  method,  as  we  have 
already  stated,  were  made  the  past  summer  against  the  root  rot 
fungus  in  the  greenhouse  and  also  in  part  of  one  of  the  badly 
infected  beds,  see  Plate  XXX,  a.  The  results  from  these  tests 
were  so  encouraging  that  we  give  the  following  tentative 
directions  for  its  use : 

It  is  perhaps  better  to  treat  the  beds  in  the  fall  so  that  they 
may  have  a  chance  to  dry  out  after  the  thorough  soaking  they 
receive.  If  treated  in  the  spring  they  should  be  aired  for  a 
week  before  planting  in  order  to  allow  the  fumes  of  the  form- 
alin to  escape  and  the  soil  to  dry  out  as  much  as  it  will. 
Whether  in  fall  or  spring,  the  bed  should  be  treated  after  the 
tillage  is  mostly  done,  for,  if  cultivated  deeply  after  the  treat- 
ment, untreated  soil  containing  the  fungus  may  be  brought  up 
from  below.  Commercial  fertilizers  may  be  used  either  before 
or  after  the  bed  is  treated,  but  manure,  if  used,  should  be  put 
on  before  so  that  it  may  be  sterilized.  Use  only  the  strongest 
formalin,  guaranteed  40  per  cent.  This  can  be  bought  in  car- 
boys holding  about  100  pounds  for  10  cents  per  pound,  or  a 
better  article  in  pint  bottles  at  about  40  cents.  It  is  not  neces- 
sary, however,  to  get  the  chemically  pure  article,  but  it  is 
necessary  to  keep  the  bottles  tightly  stoppered  to  avoid  loss  of 
strength  through  evaporation.  One  pint  of  this  formalin 
should  be  added  to  each  twelve  and  a  half  gallons  of  water 
used,  or  at  the  rate  of  one  to  one  hundred  by  volume.     This 


ROOT    ROT   OF    TOBACCO.  365 

should  be  applied  immediately  to  the  bed  with  a  sprinkling  can 
SO  as  to  evenly  and  thoroughly  wet  the  soil,  using  two-thirds 
to  one  gallon  to  each  square  foot  of  surface.  It  may  take  some 
time  for  the  soil  to  soak  in  the  latter  quantity,  but  if  applied 
in  partial  amount  it  will  soak  in  while  the  rest  of  the  bed  is 
being  treated.  The  ground  should  be  covered  with  the  sash 
or  canvas  for  a  couple  of  days  after  treatment  to  help  keep  in 
the  fumes. 

Sprinkling  seedlings  zvith  formalin.  According  to  our  obser- 
vations and  experiments,  a  very  weak  strength  of  formalin 
(about  I  to  1500)  sprinkled  several  times  on  the  plants  in  the 
infected  beds  did  not  give  very  favorable  results.  So  far  as 
the  root  rot  is  concerned  we  do  not  believe  this  treatment  has 
much  value  after  the  appearance  of  the  disease.  As  regards 
the  dampening  off  troubles  there  was  some  evidence  that  this 
method  may  have  benefited  the  beds  slightly.  Possibly  if  this 
treatment  entirely  supplanted  the  watering  throughout  the 
whole  season  of  the  beds,  it  would  prove  more  serviceable, 
especially  against  the  dampening  oif  fungi. 

Treatment  of  the  fields.  It  is  more  difficult  to  advise  as  to 
the  best  treatment  of  the  fields.  Of  course  it  is  not  desirable 
to  use  plants  from  infected  beds,  if  others  are  available.  Care 
in  this  respect,  as  stated  before,  does  not  necessarily  mean  that 
the  trouble  will  be  escaped  in  the  fields.  One  grower  has  sug- 
gested that  it  might  be  well  to  use  formalin  in  the  water  (i  to 
1200)  when  the  plants  are  set  out.  While  it  is  not  likely  that 
this  would  prove  of  any  great  service,  it  might  be  worth  trial  on 
a  small  scale,  to  determine  its  value.  Some  form  of  rotation 
may  be  found  necessary  if  the  fungus  persists  in  injuring  each 
succeeding  crop.  One  field  was  seen  the  past  summer,  part  of 
which  had  been  in  corn  the  two  previous  years,  and  this  part, 
according  to  the  owner,  did  better  than  the  remainder  of  the 
field;  an  examination  of  the  roots  also  showed  less  of  the  rot 
there.  Where  one  has  reason  to  suspect  that  his  soil  is  acid, 
it  might  be  well  to  lime  part  of  the  field  to  see  if  this  will  prove 
helpful  to  the  crop.  On  the  other  hand,  if  a  grower  has  been 
using  large  amounts  of  potash  (and  the  growers  who  used  the 
most  were  among  those  whose  fields  sufifered  most)  it  might 
be  well  to  cut  down  the  amount  used  on  part  of  his  field  and 
carefully   compare  this  part  with   the   remainder  of  the   field 


366         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

during  the  season  in  order  to   get   data   for  determining  the 
character  of  his  fertilization  another  year. 

Examination  of  specimens.  During  the  coming  season  any 
grower  who  suspects  he  has  this  trouble  in  his  seed  beds  or 
fields  is  at  liberty  to  send  specimens  of  the  plants  or  the  roots 
to  the  Experiment  Station,  at  New  Haven,  for  examination. 
In  cases  of  severe  injury  or  especial  interest,  inspection  of  the 
seed  beds  or  the  fields  will  be  made  if  desired. 

LITERATURE. 

The  following  include  all  of  the  references  in  literature,  of 
any  importance,  that  the  writer  has  found  relating  to  this 
fungus. 

1.  Aderhold,  R.    Impfversuche  mit  Thielavia  basicola  Zopf.  Arb.  Biol. 

Abt.   Land.   Fortw.   Kaiserl.   Gesundh.   4:  463-5.    1905.     [Review : 
Centr.  Bakt.  Par.  Infekt.  15:  276-7.     1905-] 

Made  artificial  cultures  and  inoculation  experiments ;  did  not 
find  it  a  very  aggressive  parasite  in  the  trials  made. 

2.  Berkeley,  M.  J.  and  Broome,    C.    E.     Notices    of    British    Fungi. 

Ann.  Mag.  Nat.  Hist.  II,  5:  461.     1850.   pi.  11,  f.  4. 

Describes  Torula  basicola  B.  &  Br.  as  a  new  species  on  base 
of  stems  of  peas  and  Nemophila  auriculata  from  King's  Cliffe, 
England. 

3.  Cappelluti-Altomare,  G.     I  semenzai  del  Tabacco  e  la   Thielavia 

basicola  Zopf.     R.  Inst.  Scafati  1902:  137-47.     [Listed:    Just  Bot. 
Zahrb.  30:   858.     1902.] 

Have  not  seen  this  reference. 

4.  Fischer,  E.     Thielavia  Zopf.     Engl.  &  Prantl  Nat.  Pflanzenf.  1^:299. 

1897. 

Describes  the  genus  and  gives  notes  on  the  single  species ; 
places  genus  under  family  Aspergillaceae  of  the  Plectascineae. 

5.  Frank,   A.    B.     Thielavia   basicola   Zopf.     Krankh.    Pflanz.    2:   278 

1896. 
Gives  a  short  general  account  of  the  fungus  as  taken  from  Zopf. 

6.  Jenkins,  E.  H.  and  Clinton,  G.  P.     Root-Rot  of  Tobacco.     Bull. 

Imm.  Inform.  Conn.  Agr.  Exp.  Stat.  4:  i-ii.    N.  1906.     [Illustr.] 
Give  a  general  account  of  this  disease  in  Connecticut. 

7.  Marchal,  E.     In  Belgien  im  Jahre  1901  beobachtete  pilzparasitare 

Krankheiten.     Zeitschr.  Pflanz.  Krankh.  12:  48.     1902.     Ibid,  12: 
239.     1902. 

Reports  Thielavia  basicola  killing  roots  of  peas  grown  in  water 
cultures. 

8.  Orton,  W.  A.     Plant  Diseases.     Yearbook  U.  S.  Dept.  Agr.  1901: 

672.    1902.    Ibid.,  1903:  554.    1904. 

Reports  Thielavia  basicola  injurious  in  tobacco  seed  beds  in 
1901  and  in  1903  in  Ohio  seed  beds. 


ROOT   ROT   OF   TOBACCO.  367 

9.  Peglion,  V.  Marciume  radicale  delle  piantine  di  Tabacco,  causato 
dalla  Thielavia  hasicola  Zopf.  Atti  Reale  Accad.  Lincei  V,  6:  52-6. 
1897.     [Reprint:    Centrb.  Bak.  3^:  580-3.     1897.] 

Gives  literature,  botanical  description  of  fungus,  and  records 
injury  in  tobacco  fields  of  Italy,  where  water-clogged  condition  of 
soil  favored  the  development  of  the  fungus. 

10.  Saccardo,   P.  A.     Thielavia   basicola  Zopf.     Sacc.    Syll.   Fung,    i: 

39.     1882.     Torula  basicola.    Ibid.,  4:  257.     1886. 

Describes  these  as  distinct  species  but  notes  under  former  that 
the  latter  is  a  conidial  stage  of  it. 

11.  Saccardo,   P.  A.     Clasterosporium  fragile    (Sorok.)    Sacc.      Sacc. 

Syll.  Fung.  4:  386.     1886. 

Places  Sorokin's  Helminthosporium  fragile  under  Clasterospor- 
ium. 
22.     Selby,  A.  D.    Diseases'caused  by  Nematodes.    Bull.  Ohio  Agr.  Exp. 
Stat.  73:    228.     1897. 

Found  Thielavia  basicola  on  roots  of  greenhouse  begonias  along 
with  nematodes. 

13.  Selby,   A.   D.      Root   Rot    (Black   Root).     Bull.    Ohio    Agr.    Exp. 

Stat.  156:  95-7.     1904.     [Illustr.] 

Gives  a  short  account  of  fungus  and  reports  it  in  Ohio  injur- 
ing tobacco  seedlings. 

14.  Selby,  A.  D.     Soil  Treatment  of  Tobacco  Plant  Beds.     Circ.  Ohio 

Agr.  Exp.  Stat.  59:  1-3.     O.  1906. 

Gives  suggestions  for  treatment  of  root  rot  based  on  experi- 
ments used  with  success  against  the  Rhizoctonia  fungus. 

15.  Shamel,  A.  D.     Another  Blight  strikes  tobacco.     Hartford  Daily 

Courant.     28  My.     1906. 

Reports  Thielavia  basicola  as  causing  serious  injury  to  seed- 
beds of  tobacco  in  the  Connecticut  valley;  recommends  sprinkling 
diseased  plants  with  weak  formalin. 

16.  Sorauer,  P.     Thielavia  basicola  Zopf.     Handb.  Pflanzenk.     2:  223- 

1886. 

Gives  short  note  on  fungus  and  gives  Helminthosporium  fragile 
Son  as  a  synonym. 

17.  Sorauer,    P.     Ueber    die    Wurzelbraune    der    Cjxlamen.     Zeitschr. 

Pflanz.  Krankh.  5:   18-20.     1895. 

Gives  account  of  injury  to  roots  of  Cyclamen  by  Thielavia  basi- 
cola. 

18.  Sorokin,  N.    Ueber  Helminthosporium  fragile  sp.  n.    Hedw.  15:  113. 

Au.  1876.     [Illustr.] 

Describes  the  chlamydospores  found  on  horseradish  roots  in 
Kazan  Bot.  Garden  as  a  new  species. 

19.  Thaxter,  R.    Fungus  in  Violet  Roots.    Ann.  Rep.  Conn.  Agr.  Exp. 

Stat.  1891:  166-7.     1892. 

Reports  this  on  violet  roots  in  Connecticut,  being  first  report  of 
the  fungus  in  America. 


368         CONNECTICUT    EXPERIMENT    STATION    REPORT,    I906. 

20.  Tubeuf  and  Smith,     Thielavia  basicola  Zopf.     Diseases  of  Plants : 

182-3.     1897. 
Give  a  short  general  account  of  the  fungus. 

21.  Winter,  G.     Thielavia.     Rab.  Krypt.  Fl.  i":  53.     1887.     [Illustr.] 

Gives    scientific    description    of    genus    and    the    single    species 
T.  basicola,  with  short  general  account  of  injury  by  latter. 

22.  Zopf,  W.     Thielavia   Zopf.     Genus  novum  Perisporiacearum.     Sitz. 

Bot.  Ver.  Prov.  Brandenb.  18:  101-5.     1876.     [Reprint:  Hedw.  16: 
1 14-7.     1877.] 

Describes    this    genus    as    new,    placing    Torula    basicola    B.    & 
Br.  under  it  as  its  only  species;    describes  four  spore  forms. 

23.  Zopf,  W.     Thielavia  basicola  Zopf.     Die  Pilze :    91.     1890. 

Have  not  seen  this  reference. 

24.  Zopf,   W.     Ueber  die  Wurzelbraune  der  Lupinen  eine  neue  Pilz- 

krankheit.  Zeitschr.  Pflanz.  Krankh.  i:  72-6.     1891.     [Illustr.] 

Gives  extended  account  of  this  fungus  previously  described  by 
him  and  a  list  of  plants  which  he  found  it  injuring. 


PLATE  XVII. 


Apple. 


a.     Combined  Winter  and  Canker  Injury,  p.  310. 


Peon)'. 


b.      Root  Injury  or  Rot,  p.  318. 
DISEASES  OF  APPLE  AND    PEONY. 


PLATE  XVIII. 


Raspberry.      X2. 


a.     Wilt  of  fruit,  showing  upper  healthy  and  lower  diseased,  p.  321. 

Tomato. 


b.     Black  Mold,  p.  329. 
FUNGI   OF    RASPBERRY  AND  TOMATO. 


PLATE  XIX. 


a.     Cankered  area  extending  on  stem  from  ground  upward. 


b.     Stem  girdled  under  ground. 


CANKER  DISEASE  OF    TOBACCO,  p.  325. 


PLATE  XX. 


a.     Showing  rot  of  stem  just  above  ground. 


b.     Showing  cankered  spots  on  older  plants. 
STEM    ROT,  Sderotinia  sp.,  OF   TOBACCO,   p.   326. 


PLATE  XXI. 


a.     Effect  of  treatment  in  preventing  Stem  Rot  fungus,  p.  328. 


b.     Dampening  off  fungus  at  work  among  3'oung  plants,  p.  326. 
FUNGI  OF  TOBACCO  SEEDLINGS. 


PLATE  XXII. 


a.     Leaf  Spot  of  Russian  Vetch,  p.  330. 


b.     Speck  Anthracnose  of  Violet,  p.  331. 
FUNGI   OF    RUSSIAN  VETCH   AND  VIOLET,    x  2. 


Healthy, 


PLATE  XXIII. 


Diseased. 


a.     Effect  of  disease  on  size  of  seedlings,   p.   334. 


b.     Showing  peculiar  malformations  of  leaves,   p.  332. 
ONION    BRITTLE. 


PLATE  XXIV. 


a.     Showing  how  disease  spread  across  end  of  field,  p.  333. 
Untreated.  +  Treated. 


b.      Showing  effect  of  treatment,  p.  335. 
ONION   BRITTLE. 


PLATE  XXV. 


a.      Untreated  rows  that  failed  to  respond  to  extra  fertilization,  p.  335. 
Plots-  43  2 


b.     Adjacent  treated  rows  photographed  at  same  time  and  size  as  a,  p.  335. 
5  4  32  I 


;'im^-  ^-"^^^^^^ 


:J.  ^^ 


c.     Results  of  treatment  on  yields  from  adjacent  rows,  p.  335. 
ONION    BRITTLE,  sliowing  untreated  and   treated  rows  in  detail. 


PLATE  XXVI. 


a.     After  having  been  scraped  oft",  this  new  growth 
was  made  in  less  than  two  weeks. 


i     * 

J 

'     '  -A 

i  " 

■ «' 

dl 

'  i  4  ''it 

t 

b.      Photo,ur;iplied  just  I2  days  after  <?,  p. 340. 
DRY   ROT    FUNGUS,  Mcru/ius  lacrvniaxs. 


PLATE  XXVII. 


a.     Showing  growth  made  on  plastering  back  of  the  wainscoting,  p.  339. 


b.     Sterile  mycelial  strands  formed  on  back  of  the  boards,  p.  339. 
DRY   ROT  FUNGUS,  Mcriilius  hurymans. 


PLATE  XXVIII. 


a.     Immature  fruiting  stage,  developing  on  front  of  board,  p.  340. 


Immature 


Mature. 


b.      Fruiting  or  spore  stage  of  the  fungus,  p.  340. 
DRY   ROT  FUNGUS,  Mcrulius  lacrvmans. 


PLATE  XXIX. 


Diseased. 


a.     Comparative  size  of  healthy  and  diseased  roots  of  seedlings,  p.  350. 


b.      Showing  badly  rotted  roots  of  seedlings.      X  2. 
ROOT    ROT,    Thidavia    Imsicola,   OF  TOBACCO. 


PLATE  XXX 


Treated. 


Untreated. 


a.     Apparent  effect  of  soil  treatment  with  formalin,  p.  354. 


b.     Showing  rot  in  the  fibrous  roots  of  a  field  plant,  p.  356. 
ROOT    ROT,    Thiclavia    basico/a,   OF  TOBACCO. 


PLATE  XXXI. 


Healthy. 


Diseased. 


a.     Appearance  of  the  fungus  on  the  large  roots  of  field   plants,  p.  356. 
Healthy.  Diseased. 


b.     Effect  of  rot  on  roots  of  mature  field  plants,  p.  35O. 


ROOT   ROT,    Thiclavia    basicola,   OF    TOBACCO. 


PLATE  XXXII. 


a.     Healthy  plants  that  became  diseased  on  transplanting  in  a  diseased  bed,  p.  362. 


b.      Diseased   plants  transplanted  in  disease-free  soil,  p.  361. 
ROOT  ROT,   Thielavia  basicola,  OF  TOBACCO. 


0(0 


State  Of  Connecticut 


REPORT 


OF 


The  Connecticut  Agricultural 
Experiment  Station 

REPORT  OF  THE  STATION  BOTANIST,  190r 

G.  P.  CLINTON,  SC.D. 

BEING  PART  VI  OF  THE  BIENNIAL  REPORT  OF  I907-I908 


CONNECTICUT 


REPORT   OF  THE  BOTANIST 

G.  R  CLINTON,  ScD. 


I.  Notes  on  Fungous  Diseases,  etc.,  for  1907,  p.  339. 
II.  Root  Rot  of  Tobacco — II,  p.  363. 
III.   Heteroecious  Rusts  of  Connecticut  having  a  Peridermium  for  their 
aecial  stage,  p.  369. 


ISSUED  MAY,  1908 


PART  VI. 

REPORT  OF  THE  BOTANIST  FOR  1907 


G.  P.  Clinton,  Sc.D. 


I.     NOTES  ON  FUNGOUS  DISEASES,  ETC.,  FOR  1907. 

GENERAL   NOTES   ON  DISEASES   PREVIOUSLY   REPORTED. 

Weather  conditions.  Even  more  so  than  the  previous  year, 
1907  v^as  characterized  by  comparatively  little  injury  to  plants 
from  fungous  diseases.  This  does  not  mean  that  it  was  an  excel- 
lent year  for  crops,  for,  on  the  contrary,  it  was  an  unusually  poor 
one,  since  the  conditions  that  proved  unfavorable  for  serious 
attacks  by  fungi  also  prevented  good  plant  growth.  These 
unfavorable  conditions  were  chiefly  those  of  the  weather.  To 
begin  with,  there  was  some  winter  injury  to  the  fruit  buds, 
especially  those  of  the  peach,  which,  except  in  restricted  localities, 
were  largely  killed  before  spring,  so  that  the  peach  crop  was  a 
practical  failure  for  the  state.  Some  injury,  too,  was  done  to  the 
young  twigs,  but  there  was  no  such  serious  injury  to  the  trees 
in  general,  as  was  experienced  during  the  winter  of  1903-04. 

The  spring  was  very  backward,  so  that  up  to  the  middle  of 
May  the  work  of  the  market  gardeners  was  about  a  month  behind 
the  usual  time.  Coupled  with  the  late  spring  were  two  unusual 
frosts  on  May  nth  and  May  21st,  which  did  considerable  damage 
to  the  exposed  tender  vegetation,  and  the  blossoms  developing  at 
that  time.  Especially  there  should  be  mentioned  frost  injury 
to  the  unprotected  early  tomatoes,  to  strawberry  and  grape 
blossoms,  and  to  the  unfolding  foliage  of  the  sycamores. 

Following  this  late  spring  came  an  unusually  dry  summer, 
including  most  of  the  months  of  June,  July  and  August.  The 
total  rainfall  for  these  months  was  only  5.49  inches,  as  compared 
with  the  average  of  12.80  inches  during  the  past  thirty- four 
years,  as  shown  by  the  records  of  the  United  States  Weather 
25 


34°  CONNECTICUT    EXPERIMENT    STATION    REPORT^    I907-I908. 

Bureau  at  New  Haven.  This  drought  was  felt  over  the  entire 
state,  but  was  especially  severe  in  certain  districts,  so  that  the 
yield  of  most  of  the  crops  was  very  materially  decreased.  The 
drought  was  not  broken  in  the  vicinity  of  New  Haven  until 
August  24th.  Fortunately,  the  fall,  both  as  to  its  length  and 
the  amount  of  moisture,  proved  fairly  favorable  for  vegetation, 
so  that  crops  which  were  not  too  severely  damaged  made  good 
gains  during  this  period.  The  more  important  of  the  previously 
reported  fungous  and  physiological  troubles  of  the  year  are 
briefly  discussed  under  the  following  heads : 

Apple,  Little  injury  was  done  by  either  the  sooty  blotch  or 
apple  scab.  On  the  other  hand,  the  fruit  speck  trouble,  first 
described  in  our  Report  for  1905,  p.  264,  was  more  conspicuous 
than  usual.  We  have  not  been  able  to  study  this  trouble  further, 
so  that  the  particular  fungus  responsible  for  it  is  still  in  doubt. 
Since  our  first  report,  we  have  had  complaint  of  it  from  Pennsyl- 
vania and  New  Hampshire,  and  this  year  it  was  said  to  have 
caused  very  considerable  damage  in  Maine.  The  writer  was  also 
told  that  it  was  a  very  common  and  injurious  trouble  with  apples 
on  the  Boston  market  the  past  season. 

Baldwin  spot  is  another  trouble  that  was  more  prominent  than 
usual.  It  was  seen  on  the  Greening,  and  some  fall  varieties,  as 
well  as  on  the  Baldwin.  The  fruit  at  storage  time  showed  little 
of  the  trouble,  though  it  soon  began  to  develop,  and  continued 
evident  up  to  the  end  of  the  season.  The  reddish-brown  diseased 
spots  often  appear  entirely  within  the  flesh,  but  may  work  out- 
ward so  as  to  form  a  slightly  sunken  discoloration  in  the  epider- 
mis, as  shown  in  the  illustration,  Plate  XVH,  a.  On  cutting  the 
apple,  the  tissue  of  these  spots  was  often  torn  rather  than  cut 
sharply  across,  indicating  a  tougher  or  more  spongy  texture. 
Microscopic  examination  revealed  no  fungous  threads  or  bacteria 
present.  The  cell  contents  were  more  or  less  disorganized,  colored 
reddish-brown  and  in  some  cases  there  was  more  starch  present 
than  in  the  surrounding  healthy  tissues.  Cultures,  attempted  both 
in  December  and  February  from  isolated  spots  in  the  interior, 
gave  absolutely  no  growth  of  any  kind,  thus  confirming  the  results 
of  previous  investigators  that  this  is  not  a  parasitic  trouble.  After 
these  spots  reach  the  surface  they  may  offer  entrance  for  fungi 
causing  true  rot,  especially  that  caused  by  the  blue  mold.  The  trou- 


NOTES    ON    FUNGOUS   DISEASES    FOR    I907.  34 1 

ble  seems  to  be  physiological,  and  possibly  bears  some  relationship 
to  the  weather,  especially  to  drought  such  as  was  experienced 
the  past  season.  It  was  suggested  by  one  grower,  whose  apples 
were  rather  badly  affected,  that  injury  by  the  aphis,  when  the 
apples  were  quite  young,  might  be  the  starting  point  of  the 
trouble. 

Market  Garden  Crops.  Early  in  the  season  some  of  the 
cucurbits,  especially  the  cucumber  and  muskmelon,  suffered  con- 
siderably from  the  bacterial  wilt,  but  this  did  not  progress,  so  that 
where  the  stand  was  sufficient  the  injury  was  not  so  great  as  was 
expected  at  first.  Onion  brittle,  or  something  very  similar  to  it, 
was  more  general  all  over  the  state  than  ever  before,  and  some  of 
the  crops  while  quite  young  were  very  severely  injured.  Further 
study  of  the  trouble  did  not  throw  any  additional  light  upon  its 
cause.  The  onion  crop  as  a  whole  was  fair,  since  seed  onions 
suffered  little,  if  any,  from  the  blossom  blight,  and  the  black  spot 
did  little  injury  to  the  bulbs  of  the  white  varieties. 

Tip  burn  was  the  only  serious  trouble  of  the  potato ;  but  this, 
because  of  the  drought,  was  so  severe  that  the  crop  was  cut  very 
short  in  many  fields.  There  was  practically  no  complaint  of  rotten 
tubers,  and  it  was  only  after  the  most  diligent  search  during  the 
entire  season  that  the  blight  fungus  was  finally  found  on  a  few 
green  vines  at  Storrs  and  at  this  station  about  the  first  of  October. 
In  the  fall,  market  potatoes  from  Maine,  however,  showed  con- 
siderable injury  from  blight,  and  were  seriously  objected  to  by 
the  buyers  for  a  time. 

During  the  drought  the  tomatoes  suffered  considerably  from 
the  point  rot  trouble,  which  was  a  frequent  source  of  complaint 
by  growers.  After  the  drought  it  was  less  evident,  which  seems 
to  indicate  that  it  was  a  physiological  rather  than  bacterial  or 
fungous  trouble.  The  Lima  bean  mildew  was  not  seen  during 
the  whole  season,  though  looked  for  in  fields  where  frequently 
it  is  very  troublesome. 

Ornamental  Plants.  No  very  serious  or  unusual  troubles  of 
ornamental  plants  were  found  other  than  those  reported  under 
new  diseases,  except  possibly  yellows  of  asters  and  the  leaf  spot 
of  the  European  horse  chestnut,  which  was  certainly  unusually 
conspicuous  after  August.  Leaf  scorch  injuries  of  shade  and 
forest  trees  due  to  the  drought  were  not  uncommon. 


342   CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

Peach.  The  leaf  fall  trouble  mentioned  in  our  last  Report,  p. 
317,  was  even  more  conspicuous  than  last  year.  A  thorough 
examination  was  made  of  one  of  the  orchards  where  it  showed 
most  prominently,  and  the  trees  were  found  with  their  wood 
severely  winter  injured,  while  those  not  suffering  were  free 
from  winter  injury.  This  winter  injury,  coupled  with  the  severe 
drought,  was,  in  our  opinion,  the  cause  of  the  trouble,  especially 
in  orchards  where  the  soil  could  not  be  thoroughly  tilled  to  con- 
serve the  moisture.  Yellows  is  another  trouble  that  showed  signs 
of  being  greatly  on  the  increase.  One  prominent  grower  estimates 
that  fifty  per  cent,  of  the  trees  in  the  state  are  now  infected  with 
yellows.  Mr.  Waite,  of  the  United  States  Department  of  Agri- 
culture, states  that  Connecticut  is  at  the  northern  end  of  an  area 
reaching  along  the  Middle  Atlantic  coast  in  which  there  is  a 
very  severe  outbreak  of  this  trouble.  Whether  or  not  the  outbreak 
in  this  state  is  as  severe  as  some  suppose,  remains  yet  to  be  seen, 
since  the  premature  development  of  the  buds  last  fall,  taken  as 
one  of  the  signs,  may  have  resulted  from  the  wet  fall  following 
the  prolonged  summer  drought. 

Tobacco.  There  was  some  complaint,  especially  in  the  region 
of  Granby,  of  injury  to  tobacco  beds  from  the  root  rot  fungus. 
Tobacco  in  the  field  finally  did  somewhat  better  than  was  expected 
after  its  injury  by  the  drought,  but  upon  curing,  the  quality  was 
said  to  be  below  the  average,  and  the  price  obtained  was  much 
lower  than  usual.  There  was  again  evident  injury  in  certain 
fields  near  Sufifield  that  could  not  be  laid  to  the  weather;  and, 
so  far  as  the  writer  could  determine,  did  not  seem  to  be  entirely 
the  work  of  the  root  rot  fungus,  but  was  possibly  due  to  unknown 
soil  conditions  of  a  chemical  nature. 

DISEASES  NEW  TO  THE  STATE. 

While  this  year  developed  few  serious  fungous  outbreaks, 
at  least  the  usual  number  of  new  diseases  were  found.  About 
one-fourth  of  these  troubles  are  of  physiological  rather  than  of 
parasitic  origin,  and  such  are  indicated  by  italicized  common 
names  in  the  following  accounts : 

APPLE,  Pirus  Mains. 

Spray  Injury.  Plate  XVII,  b.  We  have  mentioned  before 
(Report    for    1903,   p.    303)    the   ordinary    forms   of    Bordeaux 


NOTES    ON    FUNGOUS    DISEASES    FOR    I907.  343 

injury,  such  as  spotting  of  the  leaves,  and  russeting  of  the  fruit. 
Last  December  there  were  sent  to  the  station,  by  Mr.  E.  A.  Moore 
of  New  Britain,  Baldwin  apples  that  showed  a  form  of  injury 
which  we  had  not  seen  before.  These  apples  had  been 
sprayed  several  times  with  Bordeaux  and  lead,  the  last  application 
being  made  about  the  middle  of  August.  When  examined,  the 
fruit  still  showed  more  or  less  of  the  spray  in  the  stem  and  bloom 
ends.  The  injury  consisted  of  small  specks,  as  shown  in  the 
illustration,  reaching  but  slightly  beneath  the  epidermis,  and 
clustered  chiefly  at  the  bloom  and  stem  ends.  Evidently  some 
injurious  ingredient  of  the  spray  had  in  time  become  dissolved 
and  been  carried  into  the  tissues,  probably  through  the  lenticels 
or  insect  punctures,  kilHng  the  cells  with  which  it  came  in  imme- 
diate contact.  The  damage  resulting  from  this  kind  of  injury 
is  not  nearly  so  serious  as  the  more  common  forms. 

BEAN,  LIMA,  Phaseolus  lunatus. 

Chlorosis.  The  past  summer  a  trouble  of  Lima  beans  was  seen 
on  occasional  plants  that  was  somewhat  similar  in  appearance 
to  the  calico  of  tobacco.  It  shows  as  a  yellow  mottling  of  the 
tissues,  the  chlorophyll  usually  retaining  its  normal  color  in  the 
vicinity  of  the  larger  veins.  Attempts  to  produce  the  same  trouble 
on  healthy  plants  by  touching  the  leaves  with  juice  from  the 
diseased  tissue,  as  can  easily  be  done,  in  the  case  of  calico  of 
tobacco,  were  not  successful,  thus  indicating  that  the  chlorosis 
is  not  of  an  infectious  character.  Just  what  conditions  produce 
this  trouble  is  not  known,  and,  since  not  serious,  it  is  chiefly 
of  interest  because  of  its  general  resemblance  to  the  chlorosis  of 
variegated  plants. 

BELLFLOWER,  Campanula  rapunculoides. 

RusT^  Coleosporium  Campanulae  (Pers.)  Lev.  Plate  XXV. 
This  rust  was  found  in  October  causing  some  damage  to  plants 
in  a  New  Haven  nursery,  where  it  had  been  noticed  by  the 
owner  for  a  few  years  past.  The  uredinial  or.  II  stage  is  the 
one  that  does  most  injury,  since  this  is  chiefly  influential  in 
spreading  the  trouble.  It  shows  as  dusty  orange  outbreaks 
about  the  size  of  small  pinheads  scattered  or  clustered  on  the 
under  side  of  the  leaves.     Sometimes  there  is  a  slight  discolora- 


344  CONNECTICUT    EXPERIMENT   STATION    REPORT,    I907-I908. 

tion  of  the  upper  surface.  The  III  stage  occurs  late  in  the 
season,  as  very  small,  slightly  elevated,  reddish,  waxy  areas  also 
on  the  under  side  of  the  leaves.  Kellerman  has  shown  that  the 
I  stage  of  this  fungus  occurs  on  the  needles  of  the  pitch  pine,  from 
which  it  goes  to  the  Campanula.  The  III  stage  carries  it  back 
to  the  pine.  This  fungus  is  further  discussed  in  the  last  article 
of  this  Report. 

BITTERSWEET,  JAPANESE,  Celastrus  artkulatus. 

Crown  Gall,  Bacterium  tumefaciens  Sm.  &  Towns.  The 
above  is  a  new  host  for  the  crown  gall,  at  least  for  Connecticut. 
Dr.  Britton  found  the  infected  specimens  while  inspecting  a 
nursery  in  New  Haven.  The  galls  are  so  similar  to  those  found 
on  the  peach  and  other  hosts  in  this  state  that  there  is  no 
reason  for  believing  them  different  or  caused  by  a  different  agent. 
New  interest  has  been  aroused  concerning  the  crown  gall  because 
of  the  recent  publications  of  Smith  and  Townsend  (Science  25: 
671-3.  Ap.  1907.  Centr.  Bak.  Par.  Inf.,  II,  20:  89-91.  D. 
1907)  of  the  United  States  Department  of  Agriculture,  who  seem 
to  have  proved  that  crown  gall  on  its  various  hosts  is  caused 
by  the  bacterial  organism  named  above  instead  of  by  a  slime 
mold,  as  claimed  by  Toumey,  the  first  extended  investigator  of 
the  trouble.  They  were  able  to  produce  galls  on  peaches  and  a 
variety  of  other  plants  by  inoculation  with  pure  cultures  of  this 
bacterium  obtained  originally  from  galls  on  cultivated  marguerite. 

BLACKBERSY,  Ruhus  villosus. 

Rust,  Kuehneola  alhida  (Kuehn)  Magn.  This  forms  much 
less  conspicuous  and  injurious  outbreaks  than  the  orange  rust. 
which  attacks  the  same  hosts.  The  II  stage  of  the  fungus  was 
found  at  Storrs  on  leaves  of  the  cultivated  blackberry,  but  was  not 
very  prominent  on  these,  being  much  more  luxuriant  on  the  wild 
swamp  blackberry.  However,  it  sometimes  proves  an  injurious 
pest,  as  Stone  of  Massachusetts  (Ann.  Rep.  Hatch  Exp.  Stat. 
9:74.  1897)  has  reported  a  case  in  which  considerable  damage 
was  done  in  1894  to  cultivated  varieties  in  that  state.  The  II  or 
injurious  stage  shows  as  very  small,  yellowish-orange,  dusty  out- 
breaks on  the  under  surface  of  the  leaves.  The  final  article  of 
this  Report  contains  further  information  concerning  the  fungus. 


NOTES   ON    FUNGOUS   DISEASES    FOR    I907.  345 

CHESTNITT,  Castanea  sativa  americana. 

Chestnut  Bark  Disease,  Diaporthe  parasitica  Miirr.  Plate 
XVIII,  a.  Mr.  F.  V.  Stevens,  Jr.,  tree  warden  of  Stamford, 
informs  the  writer  that  the  chestnut  disease,  which  has  proved 
so  serious  in  the  vicinity  of  New  York  City  and  on  Long  Island, 
has  become  common  in  the  neighborhood  of  Stamford.  He  also 
reports  having  seen  the  trouble  in  one  or  two  other  places  in  the 
state.  Dr.  Murrill,  of  the  New  York  Botanical  Garden,  has  car- 
ried on  extended  investigations  during  the  past  three  years,  and 
finds  that  a  particular  fungus  is  responsible,  for  the  injury.  This 
fungus  produces  cankers  in  the  bark,  and  in  time  becomes  so 
general  on  an  infected  tree  as  often  to  kill  it.  While  most 
injurious  so  far  to  the  native  chestnut,  it  also  occurs  on  the 
chinquapin  and  the  European  chestnut,  but  has  been  found  only 
occasionally  on  the  Japanese. 

Both  Murrill  and  Metcalf,  of  the  United  States  Department  of 
Agriculture,  who  has  also  made  a  study  of  the  trouble,  take  a 
rather  alarming  view  of  the  danger  to  all  chestnuts  in  infected 
regions.  Mr.  Metcalf  (U.  S.  Dept.  Agr.  Bur.  PL  Ind.  Bull.  121, 
VI.  1908)  says:  "Unless  something  now  unforeseen  occurs  to 
check  its  spread,  the  complete  destruction  of  the  chestnut  orchards 
and  forests  of  the  country,  or  at  least  the  Atlantic  States,  is  only 
a  question  of  a  few  years'  time."  While  the  trouble  is  no  doubt 
a  serious  one,  we  are  inclined  to  believe  that  its  power  of  spread- 
ing and  the  likelihood  of  its  annihilating  all  the  trees  of  infected 
regions,  have  been  overemphasized.  Spraying  against  the  trouble 
seems  not  to  have  proved  either  practical  or  effective.  Pruning 
off  all  diseased  branches  has  not  always  been  successful  in 
freeing  the  trees  of  the  disease,  or  if  so,  they  have  become 
re-infected  through  the  wounds. 

Whether  or  not  the  trouble  is  the  same,  serious  injury  to 
native  chestnuts  and  chinquapins  has  been  reported  before  from 
different  parts  of  the  United  States,  We  quote  the  following 
from  an  article  by  Mr.  Jones,  of  Georgia,  which  appeared  in 
the  American  Journal  of  Science  and  Arts,  vol,  I,  page  450,  in 
1846 :  "The  present  remarks  are  particularly  directed  to  the  death 
and  disappearance  of  some  of  our  trees  and  shrubs.  The  first 
that  I  will  mention  is  the  Castanea  pumila,  which  is  a  tree  from 
ten  to  thirty  feet  in  height.    In  the  year  1825,  during  the  months 


346  CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

from  June  to  September,  I  observed  this  tree  dying  when  in  full 
leaf  and  with  fruit  half  matured.  I  examined  numerous  individ- 
uals, and  could  find  no  internal  cause  for  their  dying.  I  at  first 
attributed  it  to  the  great  fall  of  rain  which  took  place  in  the 
year  1823,  for  during  the  month  of  July  of  that  year  a  considera- 
ble quantity  of  land,  not  subject  to  overflow,  was  covered  with 
water  for  some  time,  and  the  highest  lands  were  completely 
saturated.  The  latter  part  of  1824  was  also  very  rainy.  Knowing 
that  this  tree  belongs  in  our  highest  and  driest  soils,  I  concluded 
that  it  was  owing  to  a  too  moist  state  of  the  ground.  But  since 
that  time  I  am  convinced  that  there  must  be  some  other  cause, 
for  the  tree  continues  still  to  die  up  to  the  year  1845,  and  if  the 
disease  is  not  arrested,  in  a  few  years  I  fear  it  will  be  entirely 
exterminated." 

Dr.  Mohr,  writing  more  recently,  1901,  in  Plant  Life  of  Ala- 
bama, says  concerning  the  chestnut  in  that  state :  "The  chestnut, 
usually  one  of  the  most  frequent  trees  of  these  forests,  is  at 
present  rarely  found  in  perfection.  The  older  trees  mostly  show 
signs  of  decay,  and  the  seedlings  as  well  as  the  coppice  growth 
proceeding  from  the  stump,  are  more  or  less  stunted.  It  is 
asserted  by  the  old  settlers  that  this  tree  is  dying  out  all  over  the 
mountainous  region,  where  at  the  beginning  of  the  second  half 
of  the  century  it  was  still  found  abundant  and  in  perfection." 

COW  PEA,    Vigna  sinensis. 

Leaf  Blight,  Cercospora  Dolichi  E.  &  E.  This  fungus  forms 
reddish  subcircular  or  angular  spots,  about  one-eighth  to  one- 
quarter  of  an  inch  in  diameter,  usually  scattered  over  the  leaves 
and  showing  through  on  both  surfaces.  With  age  these  spots 
sometimes  have  a  greyish  center.  By  the  aid  of  a  hand  lens  the 
fruiting  stage  of  the  fungus  can  often  be  seen  on  the  spots 
as  an  inconspicuous  coating  of  very  short  olive-black  threads. 
Two  or  three  other  species  of  Cercospora  (C  cruenta  Sacc,  C. 
Vignae  E.  &  E.,  C.  Vignae  Racib.)  have  been  described  on  species 
of  Vigna,  or  Dolichos,"  as  it  is  sometimes  called,  which  possibly 
may  not  be  distinct  from  this.  On  some  of  these  spots  a  species  of 
Alternaria  occasionally  occurs,  but  perhaps  only  as  a  saprophyte. 

Leaf  Spot,  Amerosporium  oeconomicum  E.  &  T.  A  second 
fungus  frequently  appears  on  the  same  leaves  with  the  preceding, 


NOTES    ON    FUNGOUS   DISEASES    FOR    I907.  347 

producing  very  similar  spots.  However,  the  latter  can  be  dis- 
tinguished in  its  mature  state  by  having  spots  vi^ith  a  reddish 
border  and  whitish  center  in  which  the  fruiting  stage  shows  as 
minute  black  imbedded  bodies.  In  the  N.  A.  F.  no.  2574,  on 
Dolichos  arvensis,  Ellis  &  Everhart  issued  a  specimen  which  they 
named  Amerosporium  Dolichi  E.  &  E,  n.  s.,  which  does  not  seem 
to  be  different  from  our  species  described  by  Ellis  &  Tracy  three 
years  before  (Journ.  Myc.  4:  102.  1888).  These  exsiccati  speci- 
mens plainly  show  that  the  spores  are  septate  (about  three  septa) 
when  'old,  and  the  specimens  collected  in  Connecticut  also  indicate 
that  they  would  become  septate  with  age.  This  may  mean  that 
the  fungus  belongs  in  a  different  genus,  since  the  spores  of  Amer- 
osporium are  said  to  be  continuous. 

In  the  specimens  collected  at  Storrs  in  September,  besides  the 
Cercospora  and  Amerosporium,  the  leaves  also  had  numerous 
more  or  less  elevated  reddish  spots  or  specks  the  size  of  a  pinhead 
or  less.  While  these  may  be  the  beginning  of  the  fungous 
troubles  already  mentioned,  they  look  very  much  like  injuries 
caused  by  sucking  insects.  Altogether  the  spotting  caused  by 
these  various  agents  becomes  quite  conspicuous,  and  causes 
considerable  injury  to  the  leaves. 

CURRANT,   Ribes  ruhrum. 

Bitter  Rot^  Gloeosporium  rufo-maculans  (Berk.)  Thuem. 
Plate  XVIII,  c.  During  the  latter  part  of  July,  in  a  small  plan- 
tation at  Storrs,  the  white  currant  was  found  rather  badly  affected 
with  a  fungous  trouble  that  caused  the  berries  to  gradually  shrivel 
and  dry  up  into  wrinkled  mummies.  The  fruiting  stage  of  the 
fungus  shows  under  a  hand  lens  as  minute  black  specks,  fre- 
quently with  a  lighter  center,  but  these  may  become  obscured 
by  the  small  masses  of  pinkish  spores  that  ooze  out  on  the  surface. 
At  the  same  place,  but  not  necessarily  on  the  same  bushes,  there 
was  also  found  a  small  amount  of  anthracnose,  Gloeosporium 
Ribis  (Plate  XVIII,  b),  that  often  attacks  currant  leaves.  In 
passing  it  might  be  noted  that  Klebahn  (Zeitschr.  Pflanzenkr. 
16:  65-83.  1906)  has  recently  shown  that  this  fungus  is  the 
conidial  stage  of  Pseudopesisa  Ribis  n.  s.  that  develops  on  the 
fallen  leaves  in  the  spring.  At  first  it  was  believed  that  the  fruit 
disease  was  also  caused  by  this  Gloeosporium,  although  it  is  not 


348  CONNECTICUT    EXPERIMENT    STATION    REPORT^    I907-I908. 

commonly  reported  on  the  fruit,  Stewart,  in  Bulletin  No.  199  of 
the  N.  Y.  Exp.  Station,  being  the  only  one  known  to  the  writer 
who  has  found  it  on  the  fruit  and  stems  as  well  as  on  the  leaves. 
Microscopic  examination,  however,  showed  that  the  spores  from 
the  berries  and  leaves  were  quite  different  in  appearance.  The 
spores  from  the  leaves  were  chiefly  16  —  20/x  by  5 — 6ju,,  and 
decidedly  curved,  being  usually  bow-shaped  and  often  tapering 
to  the  ends ;  while  the  spores  from  the  fruit  were  straight,  less 
tapering,  and  somewhat  narrower,  varying  chiefly  from  14  —  22/a 
by  4  —  5)U,.  So  similar  are  the  spores  to  those  of  the  bitter  rot 
fungus,  especially  to  grape  rot  mentioned  in  our  last  Report 
(1906,  p.  314),  that  we  have  decided,  at  least  for  the  present, 
to  consider  the  fungus  the  same,  though  it  has  not  before  been 
reported  on  the  currant  as  a  host.  We  have  found  no  other 
Gloeosporium  mentioned  as  occurring  on  the  fruit  of  currants, 
though  Gloeosporium  ribicolum  E.  &  E.  was  described  on  the 
fruit  of  Ribes  sp.  (cultivated  gooseberry).  A  few  days  after 
collecting  the  fungus  at  Storrs,  the  white  currants  on  the  Experi- 
ment Station  grounds  at  New  Haven  were  examined,  and  the 
fruit  of  these  was  found  to  be  somewhat  similarly  injured. 
Microscopic  examination,  however,  showed  that  in  this  case 
the  Gloeosporium  present  was  different,  the  smaller  spores  varying 
chiefly  from  7  —  I5/^  by  3  —  6/x.  As  many  of  the  shriveled  berries 
showed  no  signs  of  this  fungus,  it  is  quite  probable  that  it  occurred 
here  as  a  saprophyte,  and  the  trouble  was  really  due  to  some  other 
cause,  possibly  the  very  dry  weather.  The  spores  of  this  fungus 
were  similar  to  those  of  G.  ribicolum,  except  slightly  broader. 

Powdery  Mildew,  Sphaerotheca  mors-uvae  (Schw.)  B.  &  C. 
Plate  XIX.  While  the  powdery  mildew  has  been  reported  from 
Connecticut  on  the  gooseberry,  this  is  the  first  mention,  so  far  as 
known,  of  its  occurrence  on  the  currant.  Specimens  were  found 
in  July  on  red  currants  in  a  nursery  at  Storrs,  where  it  confined 
its  attacks  to  the  ends  of  the  young  branches  and  their  leaves, 
the  latter  being  checked  in  their  development.  At  the  same  place 
the  fungus  occurred  on  the  gooseberry,  but  limited  its  attacks  here 
to  the  fruit.  The  dirty  white  or  brownish  mycelium  forms  a 
thickish  felt  (in  which  are  imbedded  the  fruiting  bodies  as  dark 
specks)  on  the  affected  parts,  and  is  thus  directly  exposed  to 
fungicides  when  applied.     However,  to  secure  good  results,  the 


NOTES    ON    FUNGOUS   DISEASES    FOR    I907.  349 

treatment  must  be  started  before  the  appearance  of  the  trouble, 
since  the  plants  infected  in  this  case  had  been  sprayed,  apparently 
tardily,  with  Bordeaux,  with  little  effect. 

FALSE  INDIGrO,  Baptisia  australis. 

Powdery  Mildew,  Erysiphe  Polygoni  DC.  This  fungus  has 
been  noted  before  from  the  state  on  several  hosts,  such  as  the 
columbine,  crowfoot  and  pea,  but  this  is  the  very  first  report, 
apparently  from  anywhere,  of  its  occurrence  on  the  above  host. 
The  mycelium  forms  a  luxuriant  growth  on  either  side  of  the 
leaf  and  an  abundance  of  the  perithecia  were  developed.  Alto- 
gether, it  caused  considerable  disfigurement  of  the  infected  plants, 
which  were  growing  in  a  local  nursery. 

FERN,  Adiantum  Farley ense. 

Leaf  Scorch.  Plate  XX,  a,  gives  a  good  idea  of  the  appear- 
ance of  this  trouble  of  the  Farleyense  fern.  It  was  first  seen  by 
the  writer  in  the  fall  of  1902,  in  a  Connecticut  greenhouse,  where 
it  was  quite  troublesome.  Complaint  was  made  of  it  again  in 
January,  1907,  by  Mr.  A.  N.  Pierson,  a  large  grower  of  ferns  at 
Cromwell,  who  sent  specimens  for  examination.  The  trouble 
shows  on  the  leaves  as  prominent,  often  wedge-shaped,  reddish- 
brown  areas  that  extend  inward  from  the  clefts  of  the  pinnae. 
These  spots  give  a  variegated  appearance  to  the  plants,  which 
produce  a  less  luxuriant  growth,  but  otherwise  appear  in 
a  healthy  condition.  A  careful  microscopical  examination  of 
the  roots,  stems  and  leaves  showed  no  indication  of  any  bacterial 
or  fungous  parasite.  There  seemed  to  be  no  unfavorable  condi- 
tions of  the  soil  to  produce  the  injury.  It  appeared  on  the  whole 
to  be  a  physiological  trouble.  So  far  as  the  writer  could  deter- 
mine, it  seemed  to  be  a  leaf  scorch,  not  necessarily  entirely 
due  to  hot  rays  of  the  sun,  but  to  loss  of  moisture  from  the 
leaves  under  unfavorable  conditions,  such  as  too  dry  an  atmos- 
phere, sudden  changes  of  air  moisture,  etc.  A  somewhat  similar 
trouble  has  been  seen  occasionally  in  nature  where  ferns  suffered 
from  lack  of  moisture.  The  Farleyense  fern  is  very  delicate,  and, 
because  of  its  very  thin  leaf  tissues,  is  much  more  sensitive  than 
other  cultivated  ferns  to  unfavorable  conditions.     The  fact  that 


35°  CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

the  trouble  seems  to  start  near  the  veins,  and  that  under  the 
microscope  the  stomates  often  show  discoloration  before  the  sur- 
rounding cells,  indicate  that  it  is  a  trouble  connected  with  the 
inability  to  properly  control  transpiration  of  moisture.  While 
no  doubt  it  is  a  common  trouble,  and  probably  noted  before  in 
floral  writings,  the  writer  has  seen  no  mention  of  it  in  the 
literature  of  plant  diseases.  Halsted  (Ann.  Rep.  N.  J.  Exp.  Stat. 
14:  420.  1894)  describes  and  figures  a  somewhat  similar  trouble 
caused  by  a  definite  fungus  (Phyllosticta  Pteridis  Hals.),  and 
briefly  states  that  unfavorable  environment  also  often  causes  ferns 
to  die  and  turn  brown  at  their  tips.  Concerning  the  Farleyense 
trouble,  Mr.  Pierson  wrote :  "I  do  not  think  it  is  due  to  sun 
burn  or  scald,  because  the  disease,  which  we  have  always  called 
rust,  is  hardly  noticeable  in  the  summer  time,  but  rather  when 
the  cold,  damp  weather  comes  on  in  the  winter ;  particularly  is  it 
so  this  year.  These  very  same  plants  that  look  so  badly,  with 
hardly  a  perfect  leaf  on  them,  will,  by  cutting  the  old  leaves 
away,  throw  up  perfect  leaves  in  the  spring,  without  a  spot  on 
them,  and  can  be  sold  for  decorative  purposes."  This  last  state- 
ment seems  also  to  indicate  that  this  trouble  is  a  physiological 
rather  than  a  parasitic  one. 

HEMLOCK,   Tsuga  canadensis. 

Rust,  Caeoma  Ahietis-canadensis  Farl.  This  rust  shows  as 
small  orange-yellow  pustules  on  the  leaves.  Apparently  it  is  never 
injurious  to  cultivated  hemlocks,  as  it  has  only  been  found  once, 
and  then  in  very  small  amount,  on  a  tree  in  a  yard  in  Westville. 

Rust,  Peridermium  Peckii  Thuem.  Plate  XXIX,  a.  Another 
rust  quite  distinct  from  the  preceding  also  occurs  here  on  the 
hemlock.  It  forms  small,  cylindrical,  white  receptacles,  usually 
in  double  rows,  on  the  under  surface  of  the  leaves.  In  time  these 
peridia  rupture  and  discharge  the  orange-colored  spores.  The 
rust  has  been  collected  a  number  of  times  the  past  year,  both  on 
cultivated  and  native  hemlocks,  but  never  occurred  in  such 
abundance  as  to  cause  any  noticeable  injury,  though  the  few 
infected  leaves  are  shed  prematurely.  J3oth  of  these  rusts  are 
discussed  further  in  the  final  article  of  this  Report. 


NOTES    ON    FUNGOUS    DISEASES    FOR    I907.  35 1 

HERBACEOITS  PLAHTS,  Delphinium  sp.,  Funkia  sp.,  Pentstemon 
harhatus,   Valeriana  officinalis. 

Stem  Rot^  Undet.  sclerotial  fungus.  Plate  XXI.  A  serious 
soil  fungus  was  found  last  fall  in  a  New  Haven  nursery  doing 
considerable  injury  to  a  variety  of  herbaceous  plants,  especially 
to  the  Valeriana  and  Pentstemon  mentioned  above.  The  myce- 
lium attacks  the  parts  of  the  plant  at  or  near  the  surface  of  the 
ground,  frequently  rotting  off  the  stems.  In  the  fall  it  forms 
subspherical  reddish  sclerotia  both  in  the  tissues  and  in  the  soil 
nearby.  Pure  cultures  were  obtained,  and  while  the  fungus 
grows  luxuriantly,  it  has  never  produced  a  true  spore  stage.  The 
sclerotia  form  as  swellings  at  the  tips  of  clustered  threads,  and 
are  at  first  whitish,  but  soon  turn  reddish-brown  on  the  outside. 
Their  size  depends  somewhat  on  the  character  of  the  medium 
used  in  the  cultures.  Plate  XXI,  b,  shows  sclerotia  on  nutrient 
potato  agar,  which  are  quite  similar  to  those  found  in  nature, 
and  others,  grown  in  nutrient  corn  meal  agar,  which  are  much 
larger  and  more  irregular.  In  artificial  cultures  made  from  the 
sclerotia  these  give  rise  to  similar  sclerotia,  but  what  they  will 
produce  in  the  soil  has  not  yet  been  determined.  According  to 
Professor  Thaxter,  they  are  probably  the  sclerotia  of  some 
hymenomycetous  fungus. 

JUNEBERRY,    Amelanchier   canadensis. 

Rust,  Gymnosporangium  clavipes  C.  &  P.  Plate  XX,  b. 
The  I  stage  (Roestelia  aurantiaca  Pk.)  of  this  fungus  has  often 
been  seen  on  specimens  of  wild  juneberry,  but  last  July  it  was 
also  found  on  cultivated  specimens  in  the  nursery  at  Storrs.  It 
occurs  most  commonly  on  the  fruit,  the  fringed  white  receptacles, 
containing  bright  orange-colored  spores,  often  thickly  covering 
the  berries.  The  III,  or  mature  stage,  occurs  on  the  cedar,  so 
that  the  trouble  is  easily  controlled  by  excluding  this  alternate 
host. 

LAUREL,  MT.,  Kalmia  latifolia. 

Leaf  Spot,  Septoria  Kalmicola  (Schw.)  B.  &  C.  The  native 
mountain  laurel  is  often  grown  for  ornament  in  Connecticut,  and 
the  last  legislature  made  it  the  state  flower.  Any  fungus  causing 
injury  to  it  thus  becomes  of  interest.     The  leaf  spot  mentioned 


352   CONNECTICUT    EXPERIMENT    STATION    REPORT^    I907-I908. 

above  is  a  very  common  trouble  on  both  the  wild  and  cultivated 
plants.  Its  chief  injury  consists  in  greatly  marring  the  appear- 
ance of  the  leaves.  The  subcircular  spots  produced  by  it  are 
scattered  over  the  leaves,  and  reach  a  maximum  size  of  about  a 
quarter  of  an  inch,  except  when  closely  placed,  they  may  run 
together  and  form  a  more  extended  injury.  They  have  a  definite 
purplish  border,  with  a  greyish  center  on  the  upper  surface  in 
which  the  small  black  fruiting  receptacles  can  be  seen  with  the 
naked  eye.  Often  on  the  same  leaves  other  somewhat  similar 
spots  are  present,  but  are  distinguished  by  having  a  reddish- 
brown  rather  than  a  greyish  center.  The  immature  fungus  found 
on  these  could  not  be  determined,  but  the  spots  look  like  those 
of  Phyllosticta  latifoliae  E.  Si  E. 

MEADOWSWEET,  Spiraea  {Ulmaria)  sp. 

Anthracnose,  Cylindrosporium  sp.  We  have  not  been  able 
to  determine  specifically  this  leaf  fungus ;  but,  from  lack  of 
definite  fungous  walls  in  the  imbedded  receptacles,  it  seems  to 
be  a  Cylindrosporium  rather  than  a  Septoria,  though  the  spores 
are  narrower  than  those  of  C.  Filipendulae.  A  number  of  species 
belonging  to  these  two  genera  have  been  described  as  having 
Spiraea  for  a  host,  and  there  seems  to  be  some  confusion  regard- 
ing them.  This  particular  fungus  has  spores  more  or  less  curved, 
with  usually  some  indication  of  septa,  often  five  when  mature. 
The  spores  vary  in  size  from  35  —  50/^  by  2ju,.  Frequently  the 
spore  masses  can  be  seen  with  a  hand  lens  as  minute  white 
tendrils  that  have  oozed  out  on  the  upper  surface  of  the  leaves. 
The  spots  are  purplish,  most  evident  on  the  upper  surface,  rather 
thickly  placed,  and  generally  are  one-eighth  of  an  inch  or  less  in 
diameter.  This  fungus  causes  considerable  injury  to  certain  of 
the  cultivated  varieties  of  Spiraea;  the  one  mentioned  here  was 
collected  in  a  New  Haven  nursery  on  plants  labeled  Ulmaria 
purpurea  elegans. 

OAK,  WHITE,   Quercus  alba. 

Anthracnose,  Gloeosporium  canadense  E.  &  E.  This  fungus 
injures  the  leaves,  most  frequently  near  the  margins,  where  the 
tissues  die  and  dry  up  into  light  brown  areas  of  considerable 
extent.     Isolated   spots,   surrounded  by  perfectly  green  tissue, 


NOTES    ON    FUNGOUS   DISEASES    FOR    I907.  353 

also  occur.  The  trouble  is  very  similar  to  the  leaf  scorch  of 
oak,  and  often  one  is  not  entirely  sure,  even  after  a  microscopic 
examination,  which  is  which.  The  specimens  reported  here  Vv^ere 
sent  from  New  Canaan  by  Mr.  A.  L.  Benedict,  who  complained 
of  injury  to  his  trees. 

PINE,  SCOTCH,  Pinus  sylvestris. 

RusT^  Peridermium  pyriforme  Pk.  Plate  XXVIII.  The  writer 
has  recently  shown  that  this  rust  is  merely  the  first  stage  of 
Cronartium  Comptoniae  Arth.,  which  has  the  sweet  fern  for  its 
alternate  host.  The  first  stage  has  been  found  in  Connecticut 
on  the  pitch  as  well  as  the  Scotch  pine.  The  rust  on  the  Scotch 
pine  was  first  found  by  the  State  Forester,  who  had  noticed  for 
several  years  that  a  number  of  these  young  pines  in  the  state 
plantation  at  Rainbow  were  attacked  by  some  fungus.  This  rust 
occurs  only  on  the  stems,  usually  at  the  base  of  the  young  tree, 
and  as  its  mycelium  is  perennial,  appears  year  after  year  in  the 
same  specimen.  It  causes  a  slight  swelling  of  the  trunk,  and 
considerable  injury  to  the  bark  and  young  wood,  so  that  badly 
infected  young  trees  are  no  doubt  sometimes  killed.  In  time 
the  spores  are  scattered,  and  all  signs  of  the  fruiting  stage  disap- 
pear, so  that  by  the  end  of  July  the  infected  trees  are  not  readily 
detected.  The  trouble  should  be  easily  controlled  by  destroying 
infected  branches  and  young  trees  and  keeping  down  the  sweet 
fern  in  the  neighborhood.  This  fungus  is  further  discussed  in 
the  final  article  of  the  present  Report. 

PINE,  WHITE,  Pinus  Strohus. 

Pine  Blight.  Plate  XXII.  This  so-called  blight  was  one  of 
the  most  conspicuous  diseases  of  the  year,  since  it  occurred  quite 
generally  not  only  in  Connecticut,  but  over  most  of  New  England. 
More  complaints  of  the  trouble,  all  after  the  middle  of  August, 
were  received  at  the  station  than  of  any  other  for  the  year. 
Its  widespread  appearance  caused  general  alarm  and  discussion, 
and  an  extended  and  intelligent  account  of  it  appeared  in  the 
Boston  Transcript  of  August  20.  The  same,  or  a  very  similar 
trouble  has  been  under  observation  for  several  years  past  by  Pro- 
fessor Stone  of  the  Massachusetts  Experiment  Station,  who  first 
noticed  it  after  the  severe  winter  of  1903-04.  He  attributes  it  to 
26 


354  CONNECTICUT    EXPERIMENT    STATION    REPORT^    I907-I908. 

winter  injury,  and  its  prominence  the  past  year  to  the  unusually 
dry  summer.  In  our  last  Report  (1906,  p.  320)  we  mentioned 
a  case  in  this  state  which  was  also  apparently  due  to  winter 
injury.  There  is  no  question  that  the  trouble,  whether  or  not 
always  due  to  the  same  causes,  has  been  more  prevalent  this 
year  than  ever  before. 

The  most  serious  complaints  were  from  the  northwestern  part 
of  the  state,  where  many  of  the  older  trees  were  reported  as 
seriously  affected.  The  writer's  observations  were  made  after 
the  first  of  August,  chiefly  on  small  trees  from  five  to  fifteen 
feet  high  in  a  Westville  nursery  and  in  the  state  plantation  at 
Rainbow.  We  have  seen  no  sign  of  the  trouble  in  the  nursery 
seedlings.  In  most  of  the  cases  examined  the  leaves  were  killed 
from  their  tips  inward  for  about  a  third  or  two-thirds  of  their 
length,  the  dead  tissues  turning  a  reddish-brown  color.  Some- 
times there  was  an  inconspicuous  yellowish  spotting  on  the  tissue 
below  the  dead  area.  This  year's  leaves  were  the  most  frequently 
injured,  and  in  all  cases  were  undersized,  thus  indicating  the 
trouble  at  least  began  before  the  leaves  reached  maturity.  In  the 
fall  often  one  or  more  of  the  leaves  in  a  bundle  dropped  out,  and 
no  doubt  all  are  shed  prematurely.  Occasionally  a  tree  was 
seen  with  all  the  leaves  dead,  in  which  case  there  was  no  hope 
for  it,  as  usually  the  roots  were  also  dead.  Most  of  the  trees 
examined,  however,  showed  no  signs  of  injury  to  the  trunk  or 
root,  such  as  a  severe  winter  freeze  might  make ;  but  the  smallest 
fibrous  roots  were  sometimes  somewhat  dried  out,  thus  indicating 
possible  suffering  from  lack  of  moisture. 

Most  persons  have  been  inclined  to  consider  this  trouble  the 
result  of  fungous  attack.  One  firm  claims  to  have  sprayed  trees 
with  good  results.  This,  if  true,  the  writer  believes  to  be  due  to 
stopping  the  transpiration  of  water  by  clogging  the  stomates, 
rather  than  to  any  fungicidal  effect.  We  see  absolutely  no 
reason  for  believing  the  trouble  due  to  a  parasitic  fungus  on 
the  leaves.  The  fungi  found  on  the  injured  leaves  were  of  the 
nature  of  saprophytes,  being  more  or  less  tardy  in  their  appear- 
ance. Then,  too,  the  widespread  injury  to  practically  all  of  the 
leaves  of  the  affected  trees,  while  adjacent  interlocking  trees  were 
often  entirely  free,  is  against  any  such  theory.  The  dry  season 
was  also  unfavorable  for  such  a  sudden  and  widespread  injury 


NOTES    ON    FUNGOUS   DISEASES    FOR    I907.  355 

by  fungous  agents.  We  have  had  seedlings  for  several  months  in 
the  greenhouse  with  their  leaves  interlocked  with  leaves  from 
diseased  trees  with  no  sign  of  contagion.  Since  the  trouble  is 
so  general  in  its  effect  on  the  tree,  a  fungus,  if  the  cause,  would 
more  naturally  be  found  at  work  on  the  roots.  As  yet  we  have 
obtained  no  satisfactory  evidence  that  a  soil  fungus  is  the  cause 
of  the  trouble.  In  fact,  the  evidence  in  the  main  is  against  such 
a  beHef.  We  have  seen  some  dead  trees  with  a  fungous  growth 
on  their  roots  and  in  the  surrounding  soil ;  and  in  one  case  young 
pines  were  planted  in  pots  containing  soil  with  such  a  fungus, 
but  with  no  injury  to  the  pines  after  several  months'  exposure. 
There  seems  to  be  no  reason  in  the  opinion  of  the  entomologists 
who  have  examined  the  injured  trees  for  believing  that  the 
trouble  is  caused  by  insects. 

Everything  considered,  the  trouble  seems  to  be  a  physiological 
one,  brought  on  by  adverse  conditions.  In  some  cases  winter 
injury  alone  probably  accounts  for  it.  In  this  state  during  the 
past  year,  it  is  apparently  largely  due  to  the  drought ;  or  possibly 
the  late  frosts  of  May  ii  and  21  may  have  injured  the  protruding 
tips  of  the  young  leaves  and  thus  have  been  altogether  respon- 
sible for  the  unusual  prominence  of  the  trouble.  The  pine  needles 
grow  from  the  base,  so  that  the  exposed  young  tips  could  have 
been  killed. or  injured  and  a  growth  still  be  made  from  the  pro- 
tected basal  part.  In  the  case  of  the  sycamores,  which  we  know 
suffered  from  these  frosts,  the  whole  of  the  young  leaf  was 
exposed,  and  so  was  entirely  killed.  In  view  of  these  possible 
and  at  the  same  time  unusual  causes,  we  do  not  look  for  the 
trouble  to  be  so  prominent  the  coming  season  as  last  year. 

POTATO,  Solanum  tuberosum. 

Internal  Brown  Spot.  Plate  XXIII,  a.  The  writer  first 
saw  this  trouble  in  Connecticut  in  potatoes  that  were  imported 
from-  Scotland  in  1906  f6r  experimental  purposes.  It  was  espe- 
cially bad  in  the  Midlothian  Early  variety.  The  past  year  it 
was  also  found  not  uncommon  in  certain  of  Mr.  East's  numerous 
varieties,  especially  in  those  of  European  origin.  Among  the  worst 
affected  of  the  varieties  were  Sutton's  Field  Ash  Leaf,  Alderman, 
Harbinger,  Royal  Ash  Leaf  Kidney,  Britannia,  Snowball,  and 
Early  Maine,  of  which  the  last  only  is  of  American  origin.     A 


356   CONNECTICUT    EXPERIMENT   STATION    REPORT,    I907-I908. 

few  Connecticut  growers  have  complained  of  trouble  similar  to 
this,  and  Morse  (5)  also  reports  it  from  Maine  in  1907. 

The  trouble  is  in  no  sense  a  true  rot.  The  affected  tubers  may- 
or may  not  show  the  disease  on  the  outside.  Usually,  however, 
some  indication  of  its  presence  is  given  by  a  slightly  shrunken 
appearance  and  a  reddish  discoloration  of  the  skin.  When  cut 
open,  the  tubers  show  a  conspicuous  reddish  disease  of  the  tissues. 
This  may  occur  in  isolated  spots  scattered  through  the  healthy 
flesh,  having  no  apparent  connection  with  the  exterior,  or  there 
may  be  a  band  starting  from  the  exterior  and  progressing  more 
or  less  deeply  inward.  Taken  as  a  whole,  the  trouble  most  fre- 
quently starts  at  the  stem  end  and  works  toward  the  bud 
end  and  inward.  In  the  cases  where  the  trouble  shows  as  a 
band  at  the  surface,  it  can  scarcely  be  told  from  the  blight  disease 
caused  by  Phytophthora.  In  some  of  the  worst  affected  European 
varieties  the  spotting  finally  runs  all  through  the  tuber,  appearing 
much  worse  than  that  shown  in  the  illustration.  Often  the 
spots  have  a  watery  appearance,  especially  in  varieties  poor  in 
starch,  but  no  evident  wet  rot  develops  from  them. 

Microscopic  examination  shows  that  the  protoplasmic  contents, 
of  the  cells  in  the  injured  areas  are  diseased  and  discolored  red- 
dish-brown. Often  this  gives  an  appearance  as  if  the  plasmodium 
of  some  extraneous  organism  were  present.  No  evidence  of 
fungous  threads  or  bacteria  was  detected.  Attempted  cultures 
made  from  the  diseased  tissues  uniformly  gave  no  growth  of  any 
'kind,  except  in  a  few  cases  where  outside  contamination  had 
occurred.  Similar  cultural  attempts  made  by  the  writer  (I)  in 
Illinois  some  years  ago,  likewise  indicated  that  the  trouble  was 
not  of  a  parasitic  nature,  and  Stewart  of  New  York  also  failed 
to  obtain  any  parasitic  organism  from  the  diseased  tubers.  All 
of  the  investigators  in  this  country  agree  in  considering  it  a 
physiological  trouble,  and  to  the  writer  it  appears  to  be  very 
much  like  the  Baldwin  Spot  of  apples.  - 

Poor  soil,  dry  weather,  lack  of  potash  or  lime,  susceptibility  of 
certain  varieties,  etc.,  all  have  been  assigned  as  probable  or  partial 
causes.  In  this  state  last  year  the  drought  was  certainly  severe, 
but  so  far  as  observed  by  the  writer,  the  trouble  was  conspicuous 
only  in  varieties  poor  in  starch.  Stewart  (6),  v/ho  made  a  study 
of  the  disease  in  New  York  in  1895,  showed  that  it  was  not  prop- 


NOTES    ON    FUNGOUS   DISEASES    FOR    I907.  357 

abated  by  diseased  tubers,  and  others  have  had  similar  results. 
The  trouble  was  particularly  prominent  in  this  country  about 
1893-95,  as  it  was  then  reported  by  the  writer  (i)  in  Illinois, 
Green  (2)  in  Minnesota,  Stewart  (6)  in  New  York,  and  the 
United  States  Department  of  Agriculture.  It  seems  to  be  com- 
mon in  Europe,  and  according  to  Jones  (4),  it  is  not  generally 
regarded  there  as  a  parasitic  trouble.  Sutton  (7)  notes  its 
presence  in  England,  where  it  is  very  likely  to  occur  on  light 
loams  or  sandy  soils,  when  twenty  to  seventy  per  cent,  of  the 
tubers  may  be  diseased.  Helms  (3)  reported  its  presence  in 
Australia  in  1895.  The  following  are  the  references  to  this 
trouble  that  have  been  alluded  to  here: 

1.  Clinton,   G,   P.     Interior   Spotting.     111.    Agr.   Exp.    Stat.   Bull.   40: 

138-9.     1895. 

2.  Green,   S.   B.     Internal   Brown   Rot  of   Potatoes.    Minn.   Agr.   Exp. 

Stat.  Bull.  39  :   212-3.     Ibid.,  45  :    310.     1895. 

3.  Helms,    R.      Report    on    an    Investigation    into    the    Potato    Diseases 

prevalent  in  the  Clarence  River  District.     Agr.   Gaz.  N.  S.  Wales 
6:  328.     1895. 

4.  Jones,  L.  R.     Internal  Brown  Spot.    U.  S.  Dep.  Agr.  Bur.  PI.  Ind. 

Bull.  87:    12-13.     1905- 

5.  Morse,  W.  J.     Internal  Brown   Spot  of  the  Tuber.     Me.  Agr.   Exp. 

Stat.  Bull.  149:    318-21.     1907. 

6.  Stewart,   F.   C.     Internal   Browning  of   Potatoes.     N.    Y.   Agr.   Exp. 

Stat.  Bull.  loi :   78-82.     1896. 

7.  Sutton,  A.  W.     Internal  Disease.     Journ.  Roy.  Agr.  Soc.  Engl.,  Ill,  9: 

599-600.     1898. 

ScuRF^  Spondylocladium  atrovirens  Harz.  Plate  XXIII,  b-d. 
In  the  spring  of  1907  this  potato  disease  was  first  called  to  my 
attention  by  Mr.  East,  who  noticed  it  on  a  few  tubers  among  the 
many  varieties  to  be  tested  that  year  by  the  station.  It  was  also 
found  not  uncommon  that  fall  on  a  still  larger  number  of  these 
same  varieties.  While  not  a  serious  potato  trouble,  it  is  interesting 
because  it  has  not  before  been  reported  in  this  country.  It  has 
been  known  for  some  time  in  Europe,  and  apparently  was  intro- 
duced into  Connecticut  on  imported  varieties.  On  unwashed 
tubers  the  trouble  does  not  show  very  plainly,  but  on  perfectly 
clean  ones  it  appears  as  a  slightly  sunken  area,  of  greater  or 
less  extent,  which  has  a  darker  brown  color.  It  is  not  nearly  so 
conspicuous  or  injurious  as  scab,  though  it  finally  causes  the 
tubers  to  shrink  somewhat  over  the  affected  areas,  and  may  offer 
entrance  for  decay  germs. 


35^  CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

The  fungus  that  causes  this  trouble  is  usually  evident,  when 
tubers  are  kept  for  a  time  in  a  moist  chamber,  as  a  scanty  growth 
of  short,  upright,  blackish  bristles,  easily  seen  with  a  lens.  These 
are  the  conidiophores,  and  bear  irregular  whorls  of  spores  on 
their  upper  end  (see  illustration,  Plate  XXIII,  c).  The  conidio- 
phores are  dark  reddish-brown,  often  with  a  slightly  swollen 
base,  and  taper  somewhat  toward  their  free  extremity.  They 
are  septate  (6 —  i6  septa),  and  vary  in  length  from  i6o  —  425jw., 
and  in  width  from  6  —  127*.  While  stiff,  and  generally  erect, 
they  are  sometimes  somewhat  bent  or  kneed,  and  rarely  branched 
toward  their  base.  They  arise  singly,  or  more  than  one,  from 
a  knot  of  fungous  cells  which  infest  the  epidermal  cells.  The 
spores  are  reddish  or  greyish,  but  lighter  colored  than  the  coni- 
diophores, and  easily  fall  from  them.  They  vary  from  oval 
to  chiefly  obclavate,  and  are  4  —  8,  usually  6,  celled.  They  are 
fastened  to  the  conidiophore  by  the  broader  end,  and  are  usually 
acute  at  the  apex,  but  will  occasionally  be  rounded  at  both  ends. 
On  falling  off,  they  generally  show  the  point  of  attachment  as  an 
evident  dark  ring  at  their  base.  They  vary  from  23  —  52 /a,  chiefly 
30  —  40 /A  in  length,  and  from  6  —  9 /a  in  greatest  width.  In 
germination  they  put  forth  a  single  tube  at  the  pointed  end. 

This  fungus  was  apparently  first  found  and  described  in 
Vienna,  Austria,  by  Harz,  in  1871  (Einige  Neue  Hyphomyceten : 
129-30),  Frank,  in  1897  (Kampfbuch  gegen  die  Schadlinge  unsere 
Feldfriichte)  and  again  in  1898  (Ber.  Deut.  Bot.  Ges.  16:  280-1) 
called  attention  to  a  new  sterile  fungus,  named  Phellomyces  scler- 
otiophorus,  which  formed  very  minute  dark  colored  sclerotia  in 
the  epidermal  cells,  and  which  he  held  responsible  for  a  sort 
of  dry  rot  of  potatoes  under  some  conditions.  Johnson  (Econ. 
Proc.  Roy.  Soc.  Dublin  i :  161-6.  1903)  and  Smith  and  Rea 
(Trans.  Brit.  Myc.  Soc.  1903-04:  59-67)  have  also  called 
attention  to  this  Phellomyces  causing  injury  to  potatoes  in  Great 
Britain.  In  1905  Appel  and  Laubert  (Ber.  Deut.  Bot.  Ges.  27,: 
218-20)  succeeded  in  getting  these  sterile  sclerotia  to  produce  a 
fruiting  stage  which  they  recognized  to  be  the  Spondylocladium 
atrovirens  of  Harz.  In  1907  they  gave  a  further  account  of  the 
fungus  in  Arb.  Kaiserl.  Biol.  Anst.  Land.  Fortw.  5:  435-41. 

In  some  of  the  specimens  which  we  have  seen,  very  small  black- 
ish spots  or  "sclerotia"  occurred  on  the  surface  of  the  tubers  apart 


NOTES    ON    FUNGOUS    DISEASES    FOR    I907.  359 

from  and  with  the  fruiting  stage  of  the  Spondylocladium ;  these 
we  have  considered  to  be  the  Phellomyces  sclerotiophorus  of 
Frank.  These  sclerotia  are  composed  of  compacted  colored  cells 
of  the  fungus,  which  more  or  less  completely  fill  the  epidermal 
cells  (see  Plate  XXIII,  d).  The  mycelium  of  the  fungus  evidently 
at  first  does  not  penetrate  very  deeply  .into  the  tissues,  and  so 
forms  only  a  superficial  injury. 

Saccardo  (Syll.  Fung.  lo:  662)  describes  another  species  of 
Spondylocladium,  S.  ahietinum  (Zuk.)  Sacc.  on  potato  tubers, 
also  from  Vienna,  Austria,  that  very  probably  is  the  same  as 
this,  though  the  spores  are  said  to  be  only  3  —  4  septate,  but 
are  38  by  9/*.  The  spores  of  our  specimens  are  smaller  than 
the  measurements  given  by  Appel  and  Laubert  for  5.  atrovirens, 
but  agree  in  the  number  of  septa,  while  they  agree  in  size  with 
the  other  species,  but  not  in  the  number  of  septa.  Specimens  were 
sent  to  Appel,  who  states  that  he  is  not  yet  sure  whether  these 
two  species  are  distinct  or  not,  though  there  seem  to  be  at  least 
two  forms,  one  having  larger  spores  than  the  other.  If  the 
species  are  distinct,  our  specimens  apparently  belong  to  the 
smaller  spored  species. 

ROSE,  Rosa    sp. 

RusT^  Phragmidium  speciosum  Fr.  Sturgis,  in  his  Report  for 
1893,  p.  86,  mentioned  injury  to  cultivated  roses  by  another  species 
of  rust,  P.  suhcorticium,  but  this  is  the  first  note  in  the  station's 
Reports  of  the  above  species.  It  was  found  on  cultivated  roses  in 
Westville,  causing  considerable  injury  to  the  stems,  to  which  it 
was  limited.  As  usual,  only  the  III  stage  appeared  on  the 
infected  stems,  forming  small,  hard,  black  pustules,  usijally 
occurring  in  clusters. 

SWEET  PEA,  Lathyrus  odoratus. 

Dampening  Off,  Pythium  sp.,  Rhisoctonia  sp.  During  last 
July,  when  sweet  peas  were  about  one-third  to  one-half  grown, 
occasional  vines  showed  evidence  of  trouble  by  turning  yellowish, 
wilting,  and  finally  drying  up  entirely.  An  examination  of  such 
plants  .showed  that  they  were  more  or  less  separated  from  their 
roots  near  the  surface  of  the  ground  by  a  reddish-brown  rot. 
Microscopic    examination   of   the    injured   tissues    revealed    the 


360  CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

presence  of  one  or  the  other  of  the  above  fungi  as  the  cause  of 
injury.  Although  the  trouble  was  quite  common,  usually  enough 
plants  escaped  to  make  a  fair  stand.  As  manure  encourages  the 
growth  of  such  fungi,  it  should  be  used  with  care,  especially  at 
the  surface  of  the  ground.  The  cold,  backward  spring  was 
apparently  largely  responsible  for  the  unusual  amount  of  dampen- 
ing off  this  year. 

SYCAMOEE,  Platanns  occidentalis. 

,  Frost  Injury.  One  or  both  of  the  severe  frosts  of  May  ii  and 
21  severely  injured  the  unfolding  leaves  of  the  sycamore  trees 
throughout  the  state,  so  that  practically  all  of  those  out  of  the 
buds  were  killed  outright.  The  injury  was  evident  immediately 
afterward,  but  became  even  more  conspicuous  later,  when  the 
remaining  leaves  began  to  assume  some  size,  through  the  very 
scanty  foliage,  which  in  many  cases  was  confined  entirely  to  the 
tops  of  the  trees.  While  some  trees  had  all  their  leaves  killed, 
and  so  were  destitute  of  foliage  for  a  time,  most  of  them  finally 
put  forth  about  one-fourth  to  one-half  the  normal  foliage,  but 
even  then  the  injury  was  evident  all  summer.  This  injury  to  the 
sycamore  was  not  limited  to  this  state,  since  von  Schrenk  (Rept. 
Mo.  Bot.  Gard.  1907:  81-3)  has  pubHshed  a  short  article  in 
which  he  calls  attention  to  similar  injury  extending  from  the 
Mississippi  Valley  eastward.  The  writer  did  not  notice  any 
serious  damage  to  the  leaves  of  other  trees,  but  probably  the 
sycamore  leaves  were  the  only  ones  just  in  the  right  condition 
for  such  an  injury  when  the  frosts  came.  Murrill  (Journ.  N.  Y. 
Bot.  Gard.  8:  157-61.  Jl.  1907),  Lloyd  (Plant  World  10:  213. 
S.  I807)  and  Halsted  (Ann.  Rep.  N.J.  Agr.  Exp.  Stat.  1907:  381. 
1908)  have  made  the  mistake  of  attributing  this  trouble  to  the 
fungus  Gloeosporium  nervisequum,  which  frequently  injures 
the  foliage  of  sycamores. 

TOBACCO,  Nicotiana  Tabacum. 

Sumatra  Disease,  fBacterial.  Shamel  has  previously  called 
attention  to  this  trouble  in  Bulletin  150  of  this  station.  The 
seed  from  which  the  Sumatra  tobacco  was  grown  was  imported 
by  the  United  States  government  a  few  years  ago.  Last  June  Mr. 
Shamel   showed  the   writer   a   small   experimental   seed  bed  at 


NOTES    ON    FUNGOUS    DISEASES    FOR    IQO/.  36 1 

Granby  in  which  most  of  the  plants  had  been  killed  by  this 
disease;  the  surviving  plants  had  ceased  to  grow,  at  least  for 
the  time,  and  a  few  that  were  transferred  to  crocks  in  the 
greenhouse  never  made  any  further  growth.  The  injury  was 
not  exactly  like  either  the  dampening  off  troubles  or  the  root 
rot  disease.  So  far  as  could  be  determined  from  this  bed,  the 
disease  started  in  the  roots,  and  was  most  manifest  in  the  vicinity 
of  the  bundles,  up  which  it  developed  a  short  distance  above 
ground.  The  roots  and  the  base  of  the  stem,  in  time,  were  so 
severely  injured  that  most  of  the  plants  succumbed.  Those  alive 
usually  showed  the  lower  leaves,  with  a  sickly,  yellowish  color, 
and  within  their  tissues  was  sometimes  found  a  Pythium-like 
fungus,  which  was  apparently  an  after-comer.  The  disease 
appears,  on  the  whole,  like  a  bacterial  trouble  of  the  bundles, 
but  specimens  of  the  older  plants  were  not  seen  to  throw  further 
light  on  the  subject. 

Concerning  this  trouble  in  the  field,  Mr.  Shamel  in  his  bulletin 
says :  "A  field  was  set  out  with  plants  grown  from  imported 
seed,  which  were  attacked  by  a  fungous  root  disease  and  all  died 
with  the  exception  of  a  few  plants.  These  resistant  or  immune 
.plants  were  found  irregularly  over  the  field,  and  produced  ripe 
tobacco  of  excellent  quality.  All  the  other  plants  were  com- 
pletely destroyed,  with  the  exception  of  one  or  two  semi-resistant 
plants  that  produced  a  large  amount  of  seed,  but  very  few  and 
extremely  small  leaves.  The  seed  was  saved  separately  from 
the  resistant  and  semi-resistant  plants,  and  sowed  in  separate 
sections  of  the  seed  beds.  The  resistant  seeds  produced  perfectly 
resistant  plants,  both  in  the  seed  bed  and  in  the  field  where  the 
plants  were  destroyed  the  previous  year.  Most  of  the  seedlings 
from  the  semi-resistant  seed  died  in  the  seed  bed.  Enough  were 
finally  secured  to  set  out  one  or  two  rows  in  the  field.  These 
plants  grew  slowly,  some  died,  and  none  reached  maturity,  all 
having  the  characteristics  of  the  diseased  plants  in  roots,  stem  and 
leaves.  Some  of  the  resistant  seed  was  sown  on  the  seed  bed 
where  the  diseased  seedlings  had  been  destroyed,  and  this  immune 
seed  produced  perfectly  resistant  plants  under  these  circum- 
stances." 

Mr.  Shamel  seems  to  think  that  our  native  varieties  are  not 
subject  to  this  trouble,  and  so  far  it  has  not  been  found  on  them. 


362   CONNECTICUT    EXPERIMENT   STATION    REPORT^    I907-I908. 

Stevens  (N.  C.  Exp.  Stat.  Bull.  i88.  1903),  however,  has 
described  a  bacterial  wilt  of  tobacco  from  North  Carolina  that 
possibly  may  prove  to  be  the  same  as  this.  Uyeda  also  has 
described  a  similar  bacterial  trouble  from  Japan,  and  Delacroix 
from  France.  All  of  these,  however,  describe  it  as  a  field  disease, 
and  little  or  no  mention  is  made  of  its  injury  in  the  seed  bed. 

TOMATO,  Lycopersicum  esculentum. 

Chlorosis.  Last  fall  in  Westville  the  writer  saw  a  large  field 
of  tomatoes  in  which  many  of  the  plants  showed  leaves  more  or 
less  mottled  with  yellowish-green.  This  unhealthy  coloring  was 
quite  similar  to  the  injury  that  can  be  transferred  to  tomatoes 
from  calicoed  tobacco.  On  inquiry,  it  was  found  that  the  tomatoes 
had  been  severely  injured  by  the  late  frosts  of  May,  but  had 
finally  recovered  and  had  borne  a  fair  crop.  It  looked  to 
the  writer  as  if  this  chlorosis  of  the  plant  was  one  of  the  after 
effects  of  the  frost,  and  was  of  the  nature  of  the  so-called  calicoed 
tobacco,  but  whether  or  not  it  was  infectious  through  the  juice 
of  the  injured  plant  was  not  determined.  Woods  claims  that  a 
similar  trouble  in  tomatoes  can  be  produced  by  a  very  severe 
pruning  back  of  the  vines,  and  possibly  the  frost  injury  was  in 
effect  merely  such  a  pruning. 

TKTJMPET   CREEPER,  Tecoma  radicans. 

Leaf  Blight,  Cercospora  sordida  Sacc.  This  fungus  shows 
on  the  under  surface  of  the  leaves  as  small,  angular,  olive-brown 
patches,  either  distinct  or  more  or  less  run  together.  The  spore 
stage  which  forms  these  patches  consists  of  short,  dark,  olive- 
brown  conidiophores  bearing  lighter  colored  spores.  The  spores 
vary  from  linear  to  linear-obclavate,  are  smoky  tinted,  4 — 12 
septate,  straight  or  somewhat  curved,  and  range  in  size  from 
40 — 120/U,  by  2.5  —  5.5/^-  The  injury  to  the  leaf  first  shows 
on  the  upper  surface  as  a  yellowish  discoloration  which  in  time 
may  change  to  reddish-brown,  but  ordinarily  it  is  not  very 
severe.  Two  other  species  of  Cercospora  have  been  described 
from  the  United  States  on  this  same  host,  but  it  is  doubtful  if 
all  three  are  distinct. 


ROOT   ROT   OF   TOBACCO.  363 


II.    ROOT  ROT  OF  TOBACCO— II. 

In  the  Report  for  1906  the  writer  gave  a  somewhat  extended 
account  of  the  fungus  Thielavia  hasicola  (B.  &  Br.)  Zopf,  and 
the  injury  it  caused  to  cultivated  plants,  especially  to  the  tobacco 
in  Connecticut.  In  this  article  is  added  such  additional  informa- 
tion as  came  to  hand  during  the  past  season,  when  the  investiga- 
tion was  brought  to  a  close.  Dr.  E.  A.  Bessey,  of  the  Govern- 
ment's Subtropical  Laboratory  in  Florida,  writes  that  he  has 
found  this  fungus  on  the  roots  of  tobacco  sent  from  Cuba,  on 
cultivated  violets  from  the  District  of  Columbia,  on  the  garden 
pea  in  South  Carolina,  on  sugar  beets  from  Utah,  and  on  various 
plants  in  Florida.  Galloway,  in  his  book  on  violet  culture,  also 
reports  it  as  a  serious  pest  on  violet  roots.  No  doubt,  it  is  a  com- 
mon and  widely  distributed  soil  fungus,  at  least  much  more  so 
than  reports  have  hitherto  indicated. 

Cultures.  During  the  past  year  and  a  half  the  fungus  has 
been  under  observation  in  cultures  with  various  media  in  an 
attempt  to  develop  the  ascospore  stage.  This  has  not  been 
obtained,  though  the  fungus  was  grown  on  tobacco  roots  on 
which  this  stage  occurs  in  nature  in  Connecticut.  Fresh  tobacco 
roots  containing  the  fungus  were  sent  to  Professor  Thaxter, 
who  tried  to  isolate  the  ascospores  by  the  Barber  method,  and 
obtain  cultures  directly  from  them — our  cultures  having  come 
originally  from  the  endospores,  or  possibly  from  the  chlamy- 
dospores — but  he  was  not  successful  in  obtaining  such  cultures. 
Professor  Thaxter  has,  on  the  other  hand,  a  culture  of  another 
species  of  Thielavia  which  forms  the  ascospores,  but  never  the 
endospores  and  chlamydospores.  These  facts  possibly  may  indicate 
that  the  ascospore  stage  has  no  relationship  to  our  fungus,  and 
that  it  occurs  on  the  tobacco  roots  as  a  parasite  of  the  fungus 
rather  than  as  a  stage  of  it.  However,  the  mature  stage  of  certain 
other  fungi,  the  apple  scab,  for  example,  is  rarely,  if  ever, 
obtained  in  artificial  cultures,  while  the  other  stages  readily  grow 
there.  For  the  present  it  is  perhaps  best  to  consider  the  ascospore 
form  as  the  mature  stage  of  the  fungus  with  the  under- 
standing that  further  study  is  needed  to  positively  prove  this 
connection. 


364  CONNECTICUT    EXPERIMENT    STATION    REPORT^    I9O7-I908. 

Seed  beds.  There  was  more  or  less  complaint  of  the  root 
rot  in  the  tobacco  seed  beds  the  past  spring,  especially  in  the 
neighborhood  of  Granby.  Some  growers  lost  their  beds,  and 
others  gave  them  up  because  of  previous  injury,  and  made  new 
ones.  Where  it  can  be  done  conveniently,  this  is  perhaps  the 
wisest  thing  to  do.  If  it  is  of  advantage  to  retain  the  old  beds, 
our  experiments  have  shown  that  they  can  be  treated  successfully 
with  either  formalin  or  steam,  and  the  injury  will  be  largely  or 
entirely  prevented. 

Several  beds  were  treated  with  formalin  last  fall  and  spring, 
all  of  which  showed  that  the  treatment  had  done  no  harm,  and  in 
most  of  them  some  benefit  resulted  even  when  the  root  rot  or  the 
dampening  off  troubles  were  not  present  to  any  injurious  extent 
in  the  check  beds.  The  two  beds  at  Bridgewater,  mentioned  in 
our  last  Report,  p.  329,  which  were  treated  in  the  fall  of  1906  for 
the  stem  rot,  did  not  give  a  fair  idea  of  how  effective  this  treat- 
ment would  prove  for  this  trouble,  since  no  serious  injury  from 
the  stem  rot  developed  in  the  treated  or  untreated  parts  of  the 
beds  the  next  spring.  In  both  cases,  however,  the  plants  upon 
the  treated  parts  were  a  little  more  advanced  than  those  on  the 
untreated,  and  there  were  also  fewer  weeds  and  angle  worms 
in  them.  In  a  bed  treated  for  root  rot  at  Poquonock  in  the  fall, 
the  soil  had  been  covered  with  a  layer  of  sand  two  or  three 
inches  deep  just  before  the  treatment,  and  this  apparently  inter- 
fered somewhat  with  the  full  action  of  the  formalin  on  the 
infested  soil  beneath,  since  a  little  root  rot  was  found  the  next 
spring  in  the  treated  part,  though  not  as  much  as  in  the  untreated. 
The  injury  in  either  case,  however,  was  not  severe,  the  sand 
apparently,  when  spaded  in,  having  helped  the  mechanical  char- 
acter of  the  soil,  or  in  some  other  way  prevented  as  serious 
injury  to  the  tobacco  from  the  fungus  as  had  occurred  the  year 
before. 

The  most  extended  experiments  were  made  by  the  Director 
and  the  writer  in  a  bed  grown  especially  for  the  station  by  Mr. 
E.  S.  Hale  of  Portland,  and  upon  these  we  report  more  in 
detail.  This  bed,  which  was  one  that  had  been  injured  consid- 
erably by  the  root  rot  the  year  before,  was  ninety-one  feet  long 
by  six  feet  wide.  In  the  fall,  before  treatment,  it  had  been 
manured  and  tilled  in  the  usual  way,  and  in  the  spring  such  com- 


ROOT   ROT   OF    TOBACCO.  365 

mercial  fertilizers  as  were  needed  were  used.  It  was  sown  with 
sprouted  tobacco  seed  April  25,  covered  with  cloth,  and  watered 
as  needed.  The  only  difference  in  the  treatment  of  the  various 
plots  into  which  the  bed  was  divided  was  as  follows : 

(i)  In  the  fall,  November  9th,  a  twenty- five  foot  plot  vi^as  treated  with 
formalin,  strength  i  to  100  water,  this  being  sprinkled  on  at  the  rate  of  one 
gallon  to  each  square  foot. 

(2)  In  the  fall  a  seventeen  foot  plot  was  treated  with  steam  by  means 
of  a  steam  rake  whose  teeth  were  pushed  about  eight  inches  into  the  soil. 
The  rake  was  wide  enough  to  take  in  the  width  of  the  bed,  and  two 
lengths  made  the  seventeen  feet.  The  rake  was  covered  with  sacks  and 
boards  to  hold  in  the  steam.  The  treatment  with  the  first  length  was  made 
for  two  and  three-quarter  hours,  because  of  some  difficulty  with  the 
steam.  At  the  end  of  the  treatment  tests  of  the  temperature  of  the  soil 
midway  between  the  teeth  showed  an  average  at  two  inches  of  96°  C, 
at  four  inches  of  99°  C,  at  eight  inches,  97°  C,  and  at  ten  inches, 
82°  C.  Between  the  rake  and  the  boards  on  the  outside  of  the  bed  the 
temperature  was  not  nearly  so  high.  The  second  treatment  was  made 
only  for  one  and  one-half  hours,  and  probably  the  temperature  did  not 
reach  quite  so  high,  but  no  difference  in  the  plants  was  noticed  on  this 
account. 

(3)  In  the  fall  a  nine  foot  plot  was  treated  with  formalin,  strength 
I  to  200  of  water,  using  one  gallon  to  each  square  foot. 

(4)  In  the  spring,  April  i6th,  a  fourteen  foot  plot  was  treated  with 
formalin,  strength  i  to  loo,  using  two-thirds  of  a  gallon  to  each  square 
foot. 

(5)  After  the  plants  were  up,  a  ten  foot  plot  was  sprinkled  with  weak 
formalin  water,  about  i  to  1000  or  1200,  nine  times  (May  3,  15,  22,  June  i, 
8,  12,  15,  20,  25)  instead  of  being  watered,  as  was  the  rest  of  the  bed  on 
those  dates. 

(6)  A  sixteen  foot  plot  was  reserved  as  a  check;  that  is,  it  had  no 
unusual  treatment. 

The  final  results  of  these  treatments,  in  general,  were  as 
follows : 

(a)  The  steam  heated  plot  (No.  2)  produced  the  best  stand, 
with  plants  most  advanced,  though  at  the  time  for  pulling  it 
had  lost  much  of  this  lead  over  the  formalin  treated  plot  (No.  i), 
which  was  next  best,  and  had  a  fine  stand  of  plants.  The  formalin 
treated  plots  (Nos.  3  and  4),  though  somewhat  behind  plots  2 
and  I,  produced  a  good  lot  of  plants.  The  formalin  sprinkled 
plot  (No.  5)  and  the  check  or  untreated  plot  (No.  6)  were  both 
about  the  same,  and  made  a  very  poor  stand  and  groivth.  The 
contrast  between  these  two  poorest  plots  and  the  two  best  at 
pulling  time  is  shown  by  the  illustrations  in  Plate  XXIV. 


366  CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

(b)  Sprinkling  zuith  weak  formalin  (plot  5)  evidently  injured 
the  plants,  as  the  stand  was  very  uneven,  and  the  plants  small 
at  pulling  time.  This  was  possibly  due  to  the  large  number  of 
treatments,  and  began  to  show  about  the  time  of  the  third  treat- 
ment, though  by  accident  the  first  was  about  twice  as  strong  as 
the  others.  Apparently  the  sprinkling  method  is  not  of  much 
value. 

(c)  The  steam  treatment  very  materially  reduced  the  number 
of  weeds,  and  apparently  the  formalin  treatment  had  somewhat 
similar  effect.  The  formalin  and  steam  both  killed  the  angle 
worms,  and  the  latter,  undoubtedly,  wire  worms,  insects,  etc. 
The  total  number  of  weeds  taken  from  each  plot  and  the  rate 
per  square  foot  for  each  was  as  follows:  Plot  No.  i,  11 59,  a 
rate  of  8  per  square  foot;  plot  No.  2,  104,  or  a  rate  of  i  per 
square  foot;  plot  No.  3,  606,  or  a  rate  of  11  per  square  foot; 
plot  No.  4,  388,  or  a  rate  of  5  per  square  foot;  plot  No.  5,  885, 
or  a  rate  of  15  per  square  foot;  plot  No.  6,  3188,  or  a  rate  of  33 
per  square  foot.  The  rate  of  the  last  two  was  raised  considerably 
by  the  poor  growth  of  the  tobacco,  which  thus  failed  to  crowd 
out  the  weeds;  in  plot  5,  this  may  have  been  offset  by  injury 
to  the  weeds  from  the  formalin. 

(d)  The  untreated  plot  (No.  6)  had  considerable  root  rot  in 
it,  but  this  was  not  so  severe  as  to  entirely  rot  off  the  roots  of 
many  of  the  plants,  since  these  usually  retained  a  firm  hold  on 
the  ground.  In  the  formalin  plots  (Nos.  i,  3,  4)  and  the  steam 
heated  plot  (No.  2)  only  a  very  little  root  rot  was  finally  found, 
not  enough  to  cause  any  harm  whatever. 

(e)  We  do  not  believe  that  the  marked  difference  between 
these  steam  and  formalin  treated  plots  and  the  untreated  plot 
was  entirely  due  to  the  prevention  of  the  root  rot,  as  this  did 
not  seem  so  prominent  as  to  have  caused  this  difference.  It  is 
possible  that  part  of  the  difference  was  due  to  a  disturbance  of  the 
bacterial  flora  of  the  soil,  in  favor  of  the  species  more  beneficial 
to  plant  growth,  such  as  has  been  reported  in  Europe  in  the 
treatment  of  the  soil  of  vineyards  with  carbon  bisulphide. 

Conclusions.  From  all  of  the  experiments  we  have  made 
during  the  past  two  years,  we  believe  that  the  formalin  treatment 
is  a  very  efficient  and  convenient  method  of  protecting  tobacco 
beds  against  the  root  rot  and  possibly  the  dampening  off  trouble. 


ROOT   ROT   OF   TOBACCO.  367 

The  formalin  is  best  applied  in  the  fall,  after  the  beds  are  pre- 
pared for  seeding-,  but  may  also  be  used  early  in  the  spring,  if 
the  beds  are  thoroughly  aired  afterwards.  Formalin,  40  per  cent, 
strength,  used  at  the  rate  of  i  to  100  of  water,  should  be 
gradually  sprinkled  on  the  beds,  using  about  one  gallon  to  each 
square  foot  of  surface  treated.  The  bed  should  then  be  covered 
for  a  day  or  two  to  keep  in  the  fumes.  The  steam  treatment  is 
fully  as  effective  against  the  root  rot,  and  even  more  efficient  in 
kilhng  weed  seeds,  but  is  more  cumbersome  and  expensive, 
especially  if  the  necessary  apparatus  is  not  at  hand.  The  soil  in 
this  case  should  be  steamed  for  at  least  an  hour  after  the  appa- 
ratus is  in  good  running  order. 

In  the  fields.  The  drought  of  the  past  summer  had  consid- 
erable effect  on  the  growth  of  tobacco  at  that  time,  but  the  moist 
weather  coming  toward  the  end  of  August  helped  many  of  the' 
fields  to  partially  recover.  Because  of  the  drought  the  root  rot 
fungus  apparently  was  not  so  conspicuous  in  the  fields  as  last  year, 
though  no  doubt  the  injury  it  did  cause  was  more  or  less  obscured 
by  the  injury  from  the  drought.  As  in  the  previous  year,  the 
tobacco  in  the  region  of  Suffield,  especially  in  certain  fields,  suf- 
fered severely  from  root  rot  or  some  other  cause.  From  our 
examinations  there,  we  are  more  convinced  than  before  that  the 
trouble  is  not  alone  caused  by  the  root  rot  fungus,  though  this 
is  the  only  agent  of  injury  that  we  can  be  sure  of  so  far.  It 
is  very  probable,  however,  that  in  the  worst  affected  fields  such 
matters  as  fertilizers,  drainage,  poisoning  of  the  land  through 
continued  use  for  tobacco,  may  have  had  as  much  or  more  to  do 
with  the  failure  of  the  crop  than  this  fungus. 

Our  crock  experiments  (see  Report  of  1906,  p.  362)  with 
fertilizers,  etc.,  in  soil  from  two  fields  in  Suffield  that  gave  very 
poor  crops  in  1906,  did  not  throw  very  much  light  on  the  subject 
except  that  those  crocks  treated  with  formalin  gave  by  far  the 
best  plants  all  through  the  test.  At  first  the  best  plants  in  all 
the  crocks  were  apparently  those  whose  roots  were  freest  from 
'root  rot,  but  the  single  plants  finally  left  in  each  crock  at  the 
end  of  the  experiment  did  not  show  so  much  difference  in  the 
amount  of  fungus  on  their  roots  as  they  did  in  their  vigor  of 
growth.  We  have  noticed  in  the  fields,  too,  that  it  is  often 
difficult  to  entirely  explain  the  dift'erence  in  size  of  individual 


368  CONNECTICUT    EXPERIMENT    STATION    REPORT^    I907-I908. 

mature  plants  by  the  amount  of  fungus  on  their  roots.  However, 
this  possibly  may  be  explained  by  the  fact  that  the  injury  which 
counts  most  is  that  given  to  the  young  plant  when  some  main 
or  tap  root  is  rotted  off  and  thus  stunts  the  growth,  at  least  for 
the  time,  rather  than  a  general,  but  not  so  severe,  injury  distri- 
buted over  the  root  system,  and  which  in  mature  plants  might 
show  as  conspicuously  as  in  the  other  case,  so  far  as  the  total 
amount  of  root  rot  is  concerned. 

No  field  experiments  were  conducted  directly  by  this  station, 
but  the  writer  had  the  privilege  of  seeing  those  made  under 
Mr.  Shamel's  directions  at  Suffield  with  various  fertilizers,  etc. 
While  there  was  some  slight  difference  between  these  plots 
(most  prominent  in  the  plot  where  the  ground  had  been  treated 
with  formalin,  and  in  one  of  the  fertilized  plots),  there  did  not 
■seem  to  be  sufficient  difference  to  indicate  any  practical  way 
of  successfully  treating  infected  fields.  These  plots  were  part 
of  a  field  that  had  been  in  tobacco  before,  and  the  rows  con- 
tinued onto  land  that  was  new,  or  at  least,  not  in  tobacco  the 
year  before.  The  difference  in  the  size  of  the  tobacco  on  the 
new  and  the  old  land,  in  favor  of  the  new  land,  was  the  striking 
thing  to  be  seen  here,  rather  than  that  due  to  any  difference  in 
the  treatment.  In  other  instances  that  we  have  known,  the 
tobacco  on  the  new  land  seemed  to  do  much  better  than  that 
on  the  adjacent  old  land. 

Conclusions.  There  seems  to  be,  so  far  as  now  known,  no 
effective  treatment  for  a  field  in  which  the  tobacco  has  been 
gradually  going  backward  in  spite  of  good  care.  In  such  a 
case  the  best  thing  is  rotation  for  a  year  or  two.  Of  course, 
on  many  farms  the  land  available  for  tobacco  is  no  more  than 
is  needed,  and  this  is  one  of  the  reasons  why  rotation  is  not  more 
commonly  practiced.  In  such  instances  the  amount  of  injury 
the  crop  suffers  will  determine  whether  or  not  the  farmer  can 
afford  to  use  this  land  for  other  purposes.  We  saw  one  field 
last  year,  however,  where  there  was  no  question  but  that  the 
owner  would  have  saved  money  if  he  had  not  used  it  at  all,  and 
no  doubt  there  were  other  cases  of  the  same  sort. 


HETEROECIOUS    RUSTS.  369 


III.     HETEROECIOUS    RUSTS    OF     CONNECTICUT 

HAVING  A  PERIDERMIUM  FOR  THEIR 

AECIAL    STAGE. 

GENERAL   CHARACTER   OF  RUSTS. 

Appearance.  Rusts  are  among  the  most  common  and  widely 
distributed  forms  of  parasitic  fungi.  While  it  is  difficult  to 
describe  their  general  appearance  so  that  one  unacquainted  with 
the  rusts  can  readily  distinguish  them  from  other  fungi,  still 
they  do  possess  characters  by  which  the  expert  readily  recognizes 
these  fungi  with  the  naked  eye.  Perhaps  to  mention  such  com- 
mon forms  as  the  grain,  asparagus,  and  chrysanthemum  rusts, 
the  cluster-cup  of  apple,  and  the  cedar-apples  of  red  cedar,  is 
one  of  the  best  ways  to  describe  them.  In  appearance  they  more 
nearly  resemble  the  smuts  than  any  other  fungi,  and  in  some 
cases  are  easily  confused  with  these.  In  general  their  outbreaks 
occur  scattered  or  clustered  on  the  leaves  or  stems  of  plants 
(hosts),  forming  small  roundish  or  linear  spore  clusters  or  sori. 
These  sori,  as  a  rule,  are  less  dusty  and  more  highly  colored  than 
the  smuts.  Early  in  the  season  the  rusts  often  have  a  reddish, 
and  later,  a  blackish  color,  as  seen  in  the  grain  and  asparagus 
rusts,  due  to  the  production  of  different  stages. 

Stages.  The  rusts  are  fungi  that  usually  have  more  than 
one  spore  stage,  in  some  cases  having  four  different  forms.  The 
earliest  stage,  called  the  pycniwn  (O,  spermagonium),  is  the 
most  inconspicuous,  and  the  one  about  which  the  least  is  known, 
for  botanists  are  not  yet  certain  whether  it  is  a  spore  stage 
or  the  male  element  in  sexual  reproduction,  and  whether  in  either 
case  it  is  now  functional.  It  is  generally  associated  with  the  next 
stage,  often  occurring  on  the  upper  side  of  the  leaf,  while  the 
latter  occurs  on  the  lower,  and  is  usually  distinguished  as 
minute  blackish  specks  situated  on  discolored  spots.  (Plates 
XXVI,  b;  XXX,  a.)  The  next,  and  generally  considered  the 
first  spore  stage,  is  called  the  aecium  (I,  aecidium,  etc.).  This 
usually  has  a  distinct  covering  or  cup-like  receptacle  called  the 
peridhmi,  which,  when  it  opens,  becomes  toothed,  fringed,  or 
irregularly  worn  away,  disclosing  the  enclosed  mass  of  yellowish 
or  orange-colored  spores.  The  peridia  in  different  species  vary 
27 


37°      CONNECTICUT   EXPERIMENT    STATION    REPORT,    I907-I908. 

from  the  size  of  a  small  pinhead  up  to  about  one-third  of  an 
inch  in  diameter.  (Plates  XXVI ;  XXVIII,  a-b.)  The  next  stage, 
known  as  the  uredinium  (II,  uredo-stage),  usually  forms  numer- 
ous, small,  naked  outbreaks  of  reddish-brown  spore'  masses  on 
the  surface  of  the  leaves,  etc.  (Plates  XXVII,  a;  XXVIII,  c; 
XXIX,  b.)  It  is  the  stage  most  commonly  seen,  as  its  function  is 
to  spread  the  fungus  over  the  infected  plants  and  to  new  ones. 
The  last  stage,  called  the  teli-um  (III,  teleuto-stage),  is  usually 
formed  late  in  the  season,  and  is  the  one  that  generally  carries 
the  fungus  over  the  winter,  so  it  is  considered  the  mature  stage. 
(Plates  XXVII,  b;  XXVIII,  d;  XXIX,  c.)  The  sori  in  this 
case  may  be  developed  externally  on  the  plants  or  be  imbedded 
in  their  tissues,  and  so  the  spores  do  not  always  form  a  dusty 
mass  to  be  easily  scattered,  as  in  the  uredinial  stage.  With  the 
germination  of  the  telial  spores  (usually  forming  in  this  process 
very  temporary  thin-walled  secondary  spores  called  sporidia)  the 
rust  may  start  anew  the  cycle  of  its  life  history  on  successfully 
infecting  its  proper  host. 

Heteroecism.  It  will  be  seen  from  the  preceding  account  that 
rusts  possess,  in  some  cases,  a  complicated  life  history.  The  I, 
II  and  III  stages  are  so  different  that  they  were  considered  by  the 
early  botanists  as  distinct  genera  (now  known  as  form  genera), 
and  so  they  were  frequently  described  under  different  specific 
names.  When  the  life  history  of  a  rust  is  fully  determined,  all 
of  its  stages  are  then  united  under  one  name,  the  generic  name 
being  decided  by  its  telial  form.  The  relationships  of  the  rusts 
are  further  complicated  by  the  fact  that,  with  some  species, 
certain  of  their  stages  may  occur  on  one  plant  and  the  others 
on  an  entirely  different  plant.  This  is  known  as  heteroecism. 
In  such  cases  there  is  no  general  rule  by  which  a  person  can 
definitely  determine  what  hosts  the  different  stages  will  occupy, 
though  investigations  are  throwing  considerable  light  on  this 
matter.  Therefore  the  life  history  of  each  species  must  be  worked 
out  by  itself.  Clues  to  the  alternate  host  often  may  be  obtained 
by  closely  watching  the  fungus  in  nature  and  determining  what 
other  related  rusts  with  their  hosts  occur  in  the  neighborhood 
of  the  one  under  observation.  For  instance,  the  farmers  of 
England  years  ago  noticed  that  the  wheat  rust  was  worst  in 
the  neighborhood  of  barberries  having  the  cluster-cup  rust;  and 
from  this  clue  De  Bary,  the  great  German  mycologist,  by  infection 


HETEROECIOUS    RUSTS.  37 1 

experiments  on  these  two  hosts  was  the  first  to  prove  definitely 
their  relationship  and  the  phenomenon  of  heteroecism. 

Kinds  of  aecia  and  their  relationship.  With  the  heteroecious 
rusts  usually  the  O  and  I  stages  occur  on  one  host  and  the  II  and 
III  on  the  alternate  host.  The  use  of  the  I  stage  is  to  carry 
the  fungus  to  the  second  host,  that  of  the  II  stage  to  spread 
it  on  this  host,  while  the  III  stage  carries  it  back  to  the  first, 
usually  early  the  next  year.  Now,  the  I  stage,  or  aecium,  may 
have  the  spores  without  a  peridium  (when  it  comes  under  the 
form  genus  Caeoma)  ;  the  peridium  may  have  the  margin  merely 
toothed  (Aecidium)  ;  its  margin  may  be  more  or  less  decidedly 
fringed  (Roestelia)  ;  or  the  fragile  peridium  may  break  up 
rather  indefinitely  (Peridermium).  The  Caeomae  species  are 
not  very  common  in  this  country,  and  their  relationships  have  in 
but  few  cases  been  definitely  worked  out.  From  the  investiga- 
tions that  have  been  made  in  Europe  one  may  expect  that  most 
of  them  are  stages  of  the  Melampsora-like  rusts.  The  species 
of  the  Aecidia  are  very  numerous,  and  the  American  heteroecious 
forms  have  been  found  by  Arthur  and  Kellerman  to  belong 
chiefly  to  the  Pucciniae  and  Uromyces  that  inhabit  grass-like 
plants.  The  American  species  of  Roesteliae,  which  occur  only 
on  rosaceous  hosts,  through  the  studies  of  Farlow,  Thaxter, 
Arthur  and  Kern,  are  now  very  completely  connected  with  the 
species  of  Gymnosporangia,  which  occur  only  on  cedar-like  hosts. 

Relationships  of  the  P eridermia.  The  Peridermia,  some  thirty 
odd  species  of  which  Arthur  and  Kern  (5)  have  described  in 
their  recent  American  monograph,  limit  their  attacks  to  coniferous 
hosts.  In  this  form  genus  the  peridia  generally  extend  promi- 
nently above  the  tissues  of  the  host,  the  walls  are  white,  very 
fragile,  and  separate  in  a  rather  indefinite  fashion  upon  the 
wearing  away  of  the  aecia.  All  Peridermia,  apparently,  belong 
to  heteroecious  rusts,  but  so  far  the  relationship  of  less  than  a 
dozen  American  ones  to  their  telial  stage  is  known.  Added 
interest  is  given  to  the  Peridermia  because  they  are  the  aecial 
stages  of  at  least  seven  telial  genera,  as  now  understood,  namely, 
Calyptospora,  Coleosporium,  Cronartium,  Melampsorella,  Me- 
lampsoridium,  Melampsoropsis,  Pucciniastrum,  and  possibly 
Necium  and  Kuehneola  (in  case  of  K.  alhida).  It  is  with  the 
Connecticut  species  of  these  telial  genera  and  their  known  or 
possible  Peridermia  that  we  are  to  deal  especially  in  the  present 


372       CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

paper.  So  far,  in  America,  Shear  (i6)  has  shown  that  Perider- 
miuni  cerebrum  on  trunks  of  Pinus  sps.  belongs  to  Cronartium 
Quercus  on  Quercus  sps.;  Kellerman  (13),  that  Peridermium 
Rostriipi  on  leaves  of  Pinus  rigida  is  connected  with  Coleospo- 
rium  Campanulae  on  Campanula  sps. ;  and  the  writer  (6,  7),  that 
Peridermium  acicolum  on  Pinus  rigida  belongs  to  Coleosporium 
Solidaginis  on  Solidago,  etc.,  Peridermium  pyriforme  on  trunks  of 
Pinus  sps.  to  Cronartium  Comptoniae  on  Comptonia  asplenifolia, 
and  Peridermium  consimile  on  leaves  of  Picea  nigra  to  Melamp- 
soropsis  Cassandrae  on  Cassandra  calyculata.  The  probable  rela- 
tionship of  several  of  our  other  species  is  known  through  the 
work  of  European  investigators,  especially  that  of  Klebahn. 
Farlow  (9,  10)  and  others  have  suggested  possible  relationships 
of  still  other  species. 

Injury.  While  rusts  in  general  are  among  the  most  injurious 
fungi,  the  forms  discussed  here  are  none  of  them  very  serious 
pests,  at  least  in  Connecticut.  In  Europe  more  or  less  complaint 
has  been  made  of  certain  of  the  Peridermia  attacking  forest  trees. 
Stone,  a  few  years  ago,  recorded  injury  to  blackberries  in  Massa- 
chusetts by  Kuehneola  alhida,  so  far  found  here  only  once  on 
cultivated  blackberries.  The  rust  on  the  leaves  of  the  pitch 
pine  was  very  common  in  a  forest  reserved  for  landscape  effect 
at  South  Manchester,  and  caused  the  owner  some  uneasiness  lest 
it  become  of  more  serious  trouble.  A  rust  which  was  found  on 
the  trunks  of  the  Scotch  pine  in  the  state  plantation  also  would 
become  a  serious  pest  if  more  abundant,  since  its  injury  to  the 
young  tree  is  very  considerable.  While  one  or  the  other  of 
the  hosts  of  all  of  the  forms  discussed  here  are  of  some 
economic  importance,  so  far  the  injury  to  them  by  their  rusts 
has  not  been  such  as  to  attract  any  considerable  attention.  It  is 
not,  therefore,  because  we  consider  these  rusts  at  present  of 
great  economic  importance  in  the  state  that  we  have  made  a 
special  study  of  them,  but  rather  because  of  their  very  interesting 
problems  of  heteroecism  and  a  desire  to  solve  more  completely 
their  life  histories  and  to  awaken  a  more  general  interest  in  them. 

Classification.  Because  of  their  variable  number  of  stages  and 
of  the  heteroecism  of  certain  species,  the  classification  of  the  rusts 
is  more  difficult  than  that  of  most  fungi,  and  gives  a  basis  for  hon- 
est differences  of  opinion  among  investigators.  Some  botanists  lay 
more  stress  on  the  host  than  others,  thus  greatly  multiplying  the 


HETEROECIOUS    RUSTS.  373 

number  of  species.  A  further  source  of  trouble  arises  from  the 
fact  that  morphologically  similar  rusts  often  infect  entirely- 
different,  though  closely  related  hosts,  as  proved  by  infection 
experiments.  This  gives  rise  to  further  confusion,  since  some 
botanists  consider  such  rusts  as  distinct  species,  while  others 
classify  them  as  physiological  species,  or  consider  them  merely 
as  strains.  These  differences  of  opinion  cause  a  grouping  together 
of  species  and  genera  on  the  one  hand,  or  to  their  splitting  up  on 
the  other,  according  to  the  attitude  of  the  investigator.  In  this 
paper  we  have  used  the  nomenclature  of  Arthur  (2),  as  given 
in  his  recent  monograph,  because  he  has  made  the  most  extended 
and  thorough  study  of  our  American  rusts ;  and,  to  avoid 
unnecessary  confusion,  we  prefer  to  follow  his  work  until  fur- 
ther investigations  shall  have  more  definitely  determined  the 
nomenclature  and  relationships  of  the  forms  discussed. 

Species  considered.  As  stated  before,  we  deal  here  only  with 
Connecticut  rusts  supposed  to  have  a  Peridermium  for  their 
aecial  stage.  So  far  only  four  species  of  Peridermium  {P.  acic- 
oluni,  P.  pyriforme,  P.  consimile,  P.  Peckii,  Plate  XXXII,  i) 
have  actually  been  found  in  the  state.  It  is  quite  probable  that 
other  species  exist  here,  since  the  search  has  extended  only  over 
a  period  of  two  years,  and  has  not  been  made  in  the  northwestern 
part  of  the  state,  where  these  species  probably  occur  most 
abundantly.  From  their  hosts  and  distribution,  other  species 
likely  to  occur  here  are  P.  Rostrupi  on  leaves  of  Pinus  rigida, 
P.  Laricis  on  leaves  of  Larix  sps.,  P.  cerebrum  and  P.  glohosiim 
on  branches  of  Pinus  rigida,  P.  globosum  and  P.  Strobi  on 
branches  of  Pinus  Strobus,  P.  conorum-Piceae  on  cones  of  Picea 
nigra,  P.  elatinum,  which  forms  witches'  brooms,  and  P.  bal- 
sameum,  which  does  not,  on  leaves  of  Abies  balsamea.  On  the 
other  hand,  the  uredinial  or  telial  stages  of  thirteen  species  have 
been  found  in  this  state,  namely,  Coleosporium  Campanulae,  C. 
Solidaginis,  C.  Vernoniae,  Cronartium  Comptoniae,  Kuehneola 
(Chrysomyxa)  albida,  Melampsoridium  Betulae,  Melampsoropsis 
Cassandrae,  M.  Pyrolae,  Neciuni  Farlowii,  Pucciniastrum  Agri- 
moniae,  P.  minimum,  P.  pustulatum,  P.  Pyrolae.  Besides  these 
there  are  six  to  ten  other  species  that  possibly  may  be  found 
here  in  time.  See  list  at  end  of  this  article.  A  special  discussion 
of  those  already  found  here  follows. 


374      CONNECTICUT   EXPERIMENT   STATION    REPORT,    I907-I908. 
SPECIAL  DISCUSSION  OF  CONNECTICUT  SPECIES. 

I.     Coleosporium   Campanulae    (Pers.)    Lev.     (I.  P eridermium 
Rostrupi  E.  Fisch.) 

I.  Plate  XXV,  a,  (from  Ohio  Fungi  104).  The  aecial  stage 
of  this  fungus  has  not  yet  been  found  in  Connecticut.  The  fact 
that  it  occurs  on  the  same  host  as  P eridermium  acicoliim  and  is 
scarcely  to  be  distinguished  from  the  latter  may  indicate  that  it 
has  been  confused  with  this  species.  While  the  relationship 
between  a  Peridermium  on  pine  leaves  and  a  Coleosporium  on 
Campanula  was  first  shown  by  European  investigators,  Kellerman 
(13)  was  the  first  in  this  country  to  produce  Coleosporium  Cam- 
panulae from  a  Peridermium  on  Pinus  rigida,  collected  in  Ohio. 
Arthur  arid  Kern  (5,  p.  416)  later  called  the  aecial  stage  Perider- 
mium Rostrupi,  after  the  European  form,  though  previously  it 
had  not  been  considered  distinct  from  our  common  P.  acicolum. 

II,  III.  Plate  XXV,  b-c.  These  stages  have  been  found  in 
Connecticut  only  once,  in  October,  1907,  on  Campanula  rapuncu- 
loides  growing  in  a  nursery  at  Westville.  The  II  s^tage  was 
common  on  the  leaves,  causing  some  injury,  and  the  owner  stated 
that  he  had  noticed  the  rust  on  these  plants  for  a  few  years  past. 
The  writer  did  not  find  the  III  stage  on  the  plants  outdoors,  but 
it  appeared  later,  after  some  of  them  were  removed  to  the 
greenhouse  for  further  observation.  By  the  end  of  November 
the  outdoor  plants  were  entirely  dead  above  ground.  This  shows 
that  the  fungus  did  not  carry  over  the  winter  through  the  imma- 
ture uredinia  on  the  leaves,  which  in  some  plants  escape  winter 
injury.  The  III  stage,  of  course,  with  all  heteroecious  rusts,  is  of 
use  only  in  carrying  the  fungus  to  the  alternate  host,  in  this 
case,  the  leaves  of  Pinus  rigida.  There  was  little  likelihood,  how- 
ever, that  the  Peridermium  occurred  on  the  pine  trees  in  this 
vicinity,  since  these  were  watched  rather  closely  without  finding 
it.  The  question,  then,  as  to  how  the  fungus  passes  the  winter 
and  again  appears  on  the  Campanula  is  interesting.  Of  course 
it  is  barely  possible  that  this  is  accomplished  through  an  occa- 
sionally undeveloped  infection  on  the  underground  perennial 
parts.  As  the  uredinial  stage  is  hardly  to  be  distinguished  from 
that  of  the  Coleosporium  on  Solidago,  and  as  the  uredinia  of  the 
latter  were  common  in  this  neighborhood,  it  occurred  to  the 
writer   that  possibly   the   rusts   on  these  two   hosts   were   not 


HETEROECIOUS   RUSTS.  375 

distinct,  as  supposed.  The  germination  of  the  uredinial  spores 
of  the  two  (Plates  XXXII,  2),  however,  was  somewhat  different, 
those  from  the  Campanula  sending  out  irregular  and  much  more 
branched  germ  tubes  than  those  from  the  Solidago.  The  uredinial 
spores  from  the  Campanula,  too,  sown  on  Campanula,  produced 
the  II  stage  in  about  eleven  days,  but  failed  to  infect  Solidago 
rugosa  and  Aster  sps.,  upon  which  they  were  also  shown.  A 
later  attempt  to  infect  the  Campanula  with  spores  of  the  Coleos- 
porium.  from  a  species  of  Aster  likewise  failed.  The  evidence  as 
a  whole  seems  to  indicate  that  these  species  are  distinct,  and  so 
how  Coleosporium  Campanulae  passes  the  winter  in  this  nursery 
is  left  unsolved. 

2.     Coleosporium    Solidaginis    (Schw.)   Thuem.      (I.     Perider- 
mium  acicolum  Und.  &  Earle.) 

I.  Plate  XXVI.  The  earlier  writers  in  Europe,  and  even 
more  recently  in  America,  called  the  common  forms  of  Perider- 
mium  on  species  of  Pinus,  Peridermium  Pini,  sometimes  dis- 
tinguishing the  leaf  form  as  acicola  and  the  stem  form  as  corticola. 
Later  Fuckel  called  the  corticolous  form  P.  Pini  and  the  leaf  form 
P.  ohlongisporium,  and  more  recently  a  number  of  other  Euro- 
pean species  have  been  distinguished.  Arthur  and  Kern,  in  their 
Peridermium  paper,  consider  the  American  specimens  on  the 
leaves  of  Pinus  rigida,  which  they  call  P.  acicolum,  distinct  from 
the  European  species,  P.  ohlongisporium,  on  Pinus  sylvestris, 
and  the  writer  follows  their  usage,  though  not  entirely  convinced 
that  they  may  not  be  the  same.  The  European  Peridermium  was 
long  ago  connected  by  Wolff  with  a  Coleosporium  on  Senecio,  and 
the  writer  (6)  has  recently  connected  the  American  Peridermium 
with  a  Coleosporium  on  Solidago.  Though  both  rusts  possess 
different  alternate  hosts,  these  hosts  are  related,  and  as  the 
morphological  characters  of  the  various  stages  of  th'e  rusts  are 
so  similar,  it  may  be  merely  a  question  of  physiological,  rather 
than  true  specific  difference  that  distinguishes  them.  Solidago 
and  Aster  are  very  uncommon  genera  in  Europe,  and  Senecio  is 
not  so  common  here  as  in  Europe,  while  Pinus  rigida  is  an  Ameri- 
can and  Pinus  sylvestris  an  European  species.  Thus  the  rusts,  if 
the  same,  would  of  necessity  have  different  hosts  in  the  two 
countries. 


376    '  CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

P eridermium  acicolum  was  first  called  to  the  writer's  attention 
in  May,  1906,  by  Mr.  Schults,  a  forester  in  Hartford,  who  found 
it  very  abundant  on  Pinus  rigida  in  a  private  grove  at  South 
Manchester  that  was  being  developed  for  landscape  purposes. 
The  owner  was  afraid  the  rust  would  become  a  serious  pest,  and 
so  Mr.  Schults  asked  for  information  concerning  spraying  the 
trees  to  keep  it  in  check.  The  writer  advised  against  this,  but 
recommended  that  a  search  be  made  for  its  alternate  host,  which 
at  that  time  was  not  known  to  science,  and  that  this,  if  found, 
be  eradicated  as  a  means  for  keeping  the  pine  rust  under  control. 
An  examination  late  in  June,  when  the  Peridermium  on  the  pine 
was  passing  its  prime,  showed  that  Coleosporium  Solidaginis  on 
Solidago  rugosa  was  just  beginning  to  become  prominent.  This 
was  the  only  rust  present  that  could  at  all  be  connected  with  the 
Peridermium,  and  besides  occurring  on  the  above  Solidago,  it 
was  found  sparingly  on  two  or  three  other  species.  The  con- 
nection between  the  Peridermium  and  the  Coleosporium  was 
very  plainly  indicated  by  the  fact  that  the  Coleosporium  on  the 
Solidago  only  occurred  prominently  under  the  infected  pine  trees, 
and  as  the  pines  were  mostly  young,  the  branches  reaching  to  the 
ground,  several  cases  were  found  where  infected  branches  inter- 
locked with  unusually  badly  infected  plants  of  the  SoHdago. 
Upon  our  advice,  these  young  pine  trees  were  pruned  of  their 
branches  for  a  distance  of  two  to  three  feet  up  the  trunk,  and 
the  goldenrod,  especially  beneath  the  trees,  was  mowed  to  the 
ground  during  the  season.  The  next  year  an  inspection  failed  to 
show  any  rust  on  the  pines,  except  a  small  amount  on  one  or 
two  very  small  seedlings  that  were  overtopped  by  some  goldenrod. 
So  this  procedure  seems  to  be  an  effectual  method  for  control- 
ling this  rust.  So  far  as  was  observed,  the  rust  limited  its  attack  to 
the  limbs  nearest  the  ground,  and  consequently  was  not  found  on 
the  very  large  trees  with  no  branches  near  their  base.  The 
young  trees  most  badly  infected  were  on  low  ground,  with  an 
abundance  of  infected  goldenrod  around  them,  so  that  conditions 
were  unusually  favorable  for  the  development  of  the  rust  on  both 
hosts. 

Inoculation  experiments  in  the  greenhouse  were  made  during 
1906  and  1907  with  spores  of  this  Peridermium  from  different 
sources,  and  on  three  different  occasions  the  Coleosporium  was 
produced  on  plants  of  Solidago  rugosa.     The  II  stage  of  the 


HETEROECIOUS    RUSTS.  377 

Coleosporium  generally  showed  inside  of  two  weeks  after  the 
spores  were  placed  on  the  leaves,  and  later  in  the  season  the  III 
stage  appeared  in  two  cases.  In  van  Tieghem  cell  tests  of  the 
spores  their  germination  was  never  abundant,  and  in  some  cases 
entirely  failed,  though  the  spores  were  fresh.  From  these  obser- 
vations and  experiments,  there  can  be  no  question  but  that  this 
Peridermium  has  for  its  alternate  host  in  Connecticut  Solidago 
rugosa,  and  presumably  other  species  of  Solidago  and  Aster  on 
which  the  Coleosporium  occurs.  So  far  the  attempts  to  infect 
the  other  species  have  not  succeeded;  but  these  were  made  only 
with  one  other  species  of  Solidago  and  a  species  of  Aster,  and 
possibly  not  under  favorable  conditions.  It  is  possible,  however, 
that  the  Peridermium  does  not  infect  all  of  the  hosts  upon  which 
the  Coleosporium  occurs,  but  that  some  of  these  may  have 
become  infected  originally  through  the  uredinial  stage. 

The  infection  of  the  pine  leaves,  so  far  as  was  determined,  takes 
place  in  spring,  and  if  then,  only  through  the  leaves  of  that  year's 
growth.  If  this  is  correct,  it  is  the  year  after  infection  before 
the  aecial  stage  appears,  as  in  all  the  cases  examined  the  leaves 
of  the  present  year's  growth  did  not  show  the  Peridermium.  The 
other  possibilities  are  that  infection  takes  place  in  the  late  fall, 
or  in  the  very  early  spring,  before  the  leaves  of  the  year  appear. 
The  first  sign  of  the  fungus  was  detected  early  in  November  on 
a  few  leaves  which  had  fully  developed  pycnia,  the  aecia  appar- 
ently following  the  next  spring.  The  pycnia  (O,  Plate  XXVI,  b) 
are  prominent,  few  in  number,  situated  on  a  yellowish  spot  (not 
shown  in  the  illustration),  and  open  by  a  longitudinal  slit. 

While  Arthur  and  Kern  (5,  p.  414)  list  only  six  collections  of 
this  Peridermium  from  the  United  States,  one  of  which  was 
from  Connecticut,  and  limit  it  to  a  small  area  along  the  Atlantic 
Coast,  this  does  not  necessarily  mean  that  the  fungus  is  very 
rare,  since  collections  have  been  made  from  five  different  locali- 
ties in  Connecticut  alone  during  the  past  two  years.  These  were 
all  on  the  leaves  of  Pinus  rigida,  as  follows :  South  Manchester, 
May  28,  June  6,  June  29,  1906,  May  29,  1907 ;  Rowayton,  June 
4,  1906;  Rainbow,  June  15,  1907;  Storrs,  July. 22,  1907;  Union, 
August  I,  1907. 

II,  III.  Plate  XXVII.  On  the  other  hand,  the  Coleosporium 
is  a  very  common  rust,  widely  distributed  over  North  America 
on  a  large  number  of  species  of  Solidago,  Aster,  and  a  few  other 


378      CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908, 

closely  related  genera.  Arthur  (2,  p.  91)  lists  over  sixty  of 
these  hosts  that  have  been  reported  so  far.  Even  in  Connecticut 
the  Coleosporium  is  much  more  widely  and  commonly  distributed 
than  the  Peridermium,  as  shown  by  the  following-  collections 
made  during  the  past  two  years :  Aster  cordifoUus,  Poquonock, 
II,  July  20,  III,  Sept.  8,  1906;  A.  diffusus,  S.  Manchester,  II, 
Sept.  8,  1906;  A.  paniculatus,  Poquonock,  II,  Nov.  5,  1906;  A. 
vimineus,  New  Haven,  II,  Nov.  26,  1907 ;  Callistephus  hortensis, 
Kent,  II,  Oct.  29,  1906,  Storrs,  II,  Sept.  30,  1907,  Westville,  II, 
Aug.  28,  1902,  II,  Oct.  17,  1903,  II,  Oct.  25,  1905  (Britton)  ; 
Sericocarpus  asteroides,  Centerville,  II,  June  6,  1907;  Solidago 
caesia,  Poquonock,  II,  Sept.  7,  1907;  6".  canadensis.  East  Haven, 
II,  Sept.  22,  1877  (Herb.  J.  A.  Allen),  Kent,  II,  Sept.  29,  1906, 
Poquonock,  II,  Sept.  8,  1906;  S.  juncea,  Centerville,  II,  Sept.  25, 
1907;  vS*.  lanceolata,  S.  Manchester,  II,  June  29,  1906;  S. 
puberula,  Woodbridge,  III,  Sept.  13,  1879  (Herb.  J.  A.  Allen)  ; 
5.  rugosa,  Centerville,  II,  Sept.  25,  1907,  Fair  Haven,  II,  Oct. 
8,  1906,  Kent,  II,  Sept.  29,  1906,  New  Haven,  II,  Sept.  20,  1906, 
S.  Manchester,  II,  June  29,  1906,  II  and  III,  Sept.  8,  1906, 
Westville,  II,  Nov.  3,  1906,  II,  Oct.  19,  1907,  West  Willington, 
II  and  HI,  Sept.  28,  1907;  vS'.  sempervirens,  New  London,  II, 
Sept.  I,  1905,  Woodmont,  II,  Aug.  1907.  Besides  the  preceding 
hosts,  Arthur  (2,  pp.  91-2)  lists  the  following  from  this  state 
upon  which  the  fungus  has  not  been  observed  by  the  writer : 
Aster  novae-angliae,  Solidago  serotina,  and  5".  ulmifolia. 

The  data  in  the  preceding  paragraph  show  the  second  stage 
to  be  by  far  the  most  frequent,  and  that  this  occurs  more  com- 
monly in  the  fall  than  at  any  other  time  of  the  year.  A  micro- 
scopic examination  of  the  uredinial  spores  also  showed  that 
there  is  a  marked  variation,  especially  as  regards  the  abundance 
and  coarseness  of  the  echinulations,  on  the  different  hosts.  The 
extremes  in  this  respect  are  certainly  as  great  as  those  which 
exist  between  the  typical  uredinial  spores  of  this  and  other 
closely  related  species.  Just  what  this  variation  means,  we 
are  not  prepared  to  state. 

A  very  interesting  question  concerning  the  fungus  is  how 
it  passes  the  winter.  We  have  seen  that  the  first  stage  on  the 
pine  has  not  been  collected  very  frequently,  and  then  only  in 
a  limited  region  along  the  Atlantic  Coast,  while  the  stages  on 
the  goldenrod,  etc.,  are  very  widely  distributed  over  the  country, 


HETEROECIOUS    RUSTS.  379 

and  frequently  collected.  That  the  I  stage  is  no  more  necessary 
for  the  appearance  of  the  Coleosporium  than  is  the  I  stage  for 
wheat  rust,  is  made  certain  by  the  frequency  with  which  the 
Coleosporium  is  collected  in  Illinois,  where  the  Peridermium  has 
never  been  found.  Since  the  III  stage  can  infect  only  the  pine, 
how  does  the  Coleosporium.  carry  over  on  the  SoHdago,  etc.,  in 
regions  where  the  Peridermium  does  not  occur?  These  regions 
are  often  too  remote  for  infection  by  wind-blown  spores  of  the 
Peridermium,  even  if  such  were  common  enough  for  this  method 
of  infection,  neither  is  it  likely,  in  the  writer's  opinion,  that 
such  infection  comes  from  the  II  stage  gradually  working 
northward  from  southern  regions,  where  it  may  occur  the  year 
round. 

The  possibility  of  the  mycelium  of  the  fungus  being  perennial 
in  the  plants  was  not  borne  out  by  a  microscopic  examination  of 
stems  of  infected  specimens  of  SoUdago  rugosa.  Badly  infested 
specimens  of  these  were  also  marked  in  the  field,  and  after  all 
their  parts  above  ground  were  dead,  their  underground  root- 
stocks  were  placed  in  crocks  in  the  greenhouse.  Half 
a  dozen  plants  produced  from  these  were  kept  under  obser- 
vation for  nearly  a  year,  and  no  rust  ever  appeared  on  them, 
so  the  mycelium  is  certainly  not  perennial.  Of  course  it  is 
barely  possible  in  some  cases,  though  this  experiment  seemed 
to  show  that  it  was  not  a  common  method,  that  a  localized  infec- 
tion late  in  the  fall  might  take  place  (by  uredinial  spores  being 
washed  down  to  the  partially  developed  imderground  rootstocks) 
and  thus  carry  the  fungus  over  the  winter. 

In  the  writer's  opinion,  however,  there  is  no  question  but 
that  the  fungus  is  commonly  carried  over  the  winter,  in  all 
parts  of  the  country,  by  late  fall  infections  of  the  II  stage  on 
the  leaves  which  often  occur  in  rosettes,  especially  in  young 
plants,  at  the  surface  of  the  ground.  We  know  that  when 
more  or  less  protected  such  leaves  frequently  survive  the  winter 
in  Connecticut.  Asters  and  goldenrod  that  are  mowed  late  in 
the  season  send  out  great  numbers  of  basal  rosettes,  and,  in 
the  fall  as  late  as  the  first  of  December,  the  II  stage  often  occurs 
as  abundantly  on  these  as  at  any  time  in  the  year.  We  have 
collected  the  II  stage  on  such  plants  in  December,  January, 
February,  March  and  April.  Germination  tests  of  the  uredinial 
spores  collected  late  in  January  gave  as  vigorous  and  abundant 


380       CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

germinations  as  at  any  time  of  the  year.  No  doubt  some  of  these 
infections  occur  so  late  that  the  sori  are  not  developed  until 
spring,  since  by  the  first  of  April  the  mature  sori  found  are 
not  numerous.  One  of  the  earliest  spring  infections  of  Coleos- 
porium  we  have  found  was  on  April  29th,  on  Solidago  sp.  and 
Sericocarpns  asieroides,  where  the,  new  sori  occurred  only  on 
the  lower  leaves,  indicating  that  these  infections  had  come  from 
sori  or  mycelia  wintering  over  on  the  surviving  basal  leaves. 

3.  Coleosporiiim  Vernoniae  B.  &  C. 
We  have  never  found  this  species  in  Connecticut,  but  Arthur 
(2,  p.  89)  lists  a  specimen  on  Vernonia  novehoracensis  from  this 
state.  It  is  a  rather  common  fungus  on  species  of  Vernonia  in 
the  Middle  West,  where  these  hosts  are  more  common  than  here. 
The  I  stage  is  not  known,  and  so  far,  apparently,  no  suggestions 
have  been  made  concerning  it,  though  the  connections  of  related 
species  indicate  that  it  is  a  Peridermium  on  the  leaves  of  some 
species  of  Pinus. 

4.  Cronartium  Comptoniae  Arth.  (I.  Peridermium 
pyriforme  Pk.) 
I.  Plate  XXVIII,  a-b.  Ever  since  proving  the  connection 
between  the  Peridermium  on  pine  leaves  and  the  Coleosporium 
on  Solidago,  we  have  been  on  the  lookout  for  a  Peridermium 
on  the  stems  of  pines  to  connect  with  the  only  species  of  Cronart- 
ium (on  sweet  fern)  that  occurs  in  this  state,  since  the  work 
of  various  investigators  has  shown  that  the  corticolous  forms 
of  Peridermia  occurring  on  pine  are  the  aecial  stages  of  Cro- 
nartia.  Mr.  Hawes,  the  state  forester,  gave  the  first  clue  to 
the  occurrence  of  the  Peridermium  on  pine  trunks  when,  on 
questioning,  he  recalled  that  he  had  seen  some  fungus  that 
worked  on  certain  of  the  pine  trees  in  the  state  plantation  at  Rain- 
bow. He  agreed  to  watch  for  this  fungus,  and  early  in  June, 
1907,  sent  specimens  of  Pinus  sylvestris  that  were  badly  infected 
with  a  Peridermium  that  proved  to  be  P.  pyriforme  Peck.  The 
writer  visited  the  plantation  June  15th  and  found  about  a  dozen 
trees,  five  or  six  years  old,  that  were  badly  infected  with  the 
Peridermium.  These  trees  were  in  a  clearing  near  a  small  grove, 
but  a  careful  search  of  this  failed  to  show  any  rust  on  the 
sweet  fern  (Comptonia  as pleni folia)  growing  there,  or  the  Peri- 


HETEROECIOUS    RUSTS.  38 1 

dermium  on  the  native  trees  of  Pinus  rigida  upon  which  P.  pyri- 
forme  ordinarily  occurs.  As  the  rust  had  been  noticed  at  least 
two  or  three  years  on  the  infected  pines,  and  as  they  had  been 
grown  in  seed  beds,  a  mile  or  two  away,  very  close  to  which 
the  sweet  fern  occurred,  there  was  no  question  but  that  they 
had  been  infected  before  transplanting  while  very  young.  A 
short  time  later  the  writer  learned  that  this  same  Peridermium 
had  been  found  at  Storrs,  on  native  specimens  of  Pinus  rigida, 
by  Mr.  Graff,  a  botanical  student,  and  on  July  21st,  through  the 
kindness  of  Dr.  Blakeslee  and  Dr.  Thom,  specimens  were  col- 
lected in  this  locality.  On  Aug.  ist,  specimens  were  also  found 
in  the  state  forest  at  Union  on  the  same  host. 

The  Peridermium  is  perennial  in  the  trunks  of  the  infected 
host,  and  does  considerable  injury  to  the  young  specimens, 
stunting  their  growth,  and  probably,  in  severe  cases,  killing 
them.  In  all  the  specimens  seen,  the  fungus  occurred  only  on 
young  trees,  less  than  fifteen  feet  in  height.  In  all  of  these  it 
was  confined  to  the  lower  branches,  usually  next  the  main 
trunk,  and  in  the  very  young  trees,  to  the  base  of  the  main 
trunk  and  its  branches.  It  caused  a  slight  swelling,  and  seemed  to 
be  confined  chiefly  to  the  bark  and  outer  wood.  When  in  its 
prime  the  Peridermium  is  conspicuous,  the  peridia  being  much 
larger  than  any  of  the  other  forms  found  here,  and  they  are 
crowded  together,  encircling  the  infected  stem,  and  extending  up 
some  distance  upon  it.  The  interlocking  teeth  or  spiny  processes 
(see  illustration,  Plate  XXVIII,  b)  that  show  when  the  peridia 
break  open,  are  also  a  distinguishing  character.  The  orange 
spore  mass  is  gradually  emptied,  and  the  peridia  flake  away, 
finally  leaving  few  signs  by  which  the  infected  trees  can  be 
detected.  This  Peridermium  is  found  from  the  first  of  June 
until  the  last  of  July. 

Arthur  (4),  in  a  recent  paper,  mentions  receiving  specimens  of 
the  Peridermium  from  Dr.  Thom  of  Storrs,  and  noting  the 
possible  relationship  to  Cronartiiim  Comptoniae,  suggests  inocu- 
lation experiments  by  those  favorably  situated  to  prove  this 
relationship.  Some  time  before,  however,  the  writer  had  already 
proved  this  connection  by  indoor  inoculation  experiments  in 
two  different  tests.  In  each  case  spores  from  the  peridia  found 
on  Pinus  sylvestris  were  sown  on  the  leaves  of  Comptonia 
asplenifolia,   and  in   about  twelve   days  the   uredinia  began   to 


382       CONNECTICUT   EXPERIMENT    STATION    REPORT,    I907-I908. 

appear.  Spores  sown  on  species  of  Solidago  and  Quercus  pro- 
duced no  result.  Curiously  enough  in  several  germination  tests 
in  water  in  van  Tieghem  cells,  the  spores  failed  entirely  to 
germinate.  From  our  experience  with  the  spores  of  the  differ- 
ent species  of  Peridermia,  however,  we  have  always  found  them 
difficult  to  germinate  in  this  way.  The  relationship  of  the 
Peridermium  and  Cronartium  was  plainly  indicated  both  at 
Storrs  and  Union,  since  the  infected  pitch  pine  trees  were  sur- 
rounded by  sweet  fern  upon  which  the  rust  was  common,  while 
it  was  not  found  elsewhere  in  the  neighborhood  at  that  time. 
This,  and  our  infection  experiments,  also  show  that  the 
Peridermia  on  the  pitch  and  Scotch  pines  are  the  same  species. 

II,  III.  Plate  XXVIII,  c-d.  This  Cronartium  has  been  found 
along  the  Atlantic  States  from  Canada  to  North  Carolina,  but 
only  on  the. sweet  fern  and  a  related  species.  In  this  state,  the 
II  stage  begins  to  appear  about  the  middle  of  July,  while  the 
telial  stage  can  be  looked  for  about  the  end  of  August.  The 
uredinia  show  as  very  small,  dusty,  yellowish  pustules  on  the 
under  surface  of  the  leaves,  while  the  telia  are  slender,  reddish, 
hair-like  growths,  more  or  less  clustered  into  tufts,  as  shown 
somewhat  poorly  in  the  illustration.  So  far,  in  Connecticut,  we 
have  seen  the  Cronartium  on  the  sweet  fern  only  in  the  neigh- 
borhood of  infected  pine  trees.  This,  and  its  somewhat  limited 
distribution,  indicate  that  the  rust  does  not  commonly  carry  over 
the  winter  on  this  host,  and  so  would  depend  each  year  on  renewed 
infection  from  the  aecial  stage.  So  far  as  we  know,  too,  the 
leaves  of  the  sweet  fern  do  not  survive  the  winter,  so  that  the  II 
stage  would  not  be  carried  over  on  them. 

This  rust  has  been  com.monly  known  in  this  country  as  Cronart- 
ium asclepiadeum  (Willd.)  Fr.,  a  species  which  occurs  in  Europe. 
This  is  probably  the  correct  view  rather  than  that  of  Arthur, 
who  considers  it  as  strictly  an  American  species.  The  infection 
experiments  made  in  Europe  by  Klebahn  and  others  have  shown 
that  the  aecial  stage  can  produce  the  Cronartium  on  a  number  of 
hosts  not  very  closely  related,  one  of  which  is  an  African  plant 
from  a  region  in  which  the  fungus  never  has  been  found.  This 
wide  range  of  hosts,  and  the  facts  that  the  different  stages  of  the 
Cronartmm  asclepiadeum  in  Europe  are  at  least  similar  in 
appearance  to  those  of  the  American  Cronartium,  and  that  Pinus 
sylvestris  is  a  host  for  the  aecial  stage  in  both  places,  all  indicate 


HETEROECIOUS    RUSTS.  383 

the  identity  of  the  species.  However,  successful  inoculation  of 
one  of  the  European  telial  hosts  with  the  American  Peridermium 
is  needed  to  decide  the  matter  finally. 

5.     Kuehneola  alhida  (Kuehn)  Magn. 

The  above  rust  is  commonly  known  under  the  name  Chrys- 
omyxa  alhida  Kuehn.  There  seems  to  be  some  doubt  as  to  its 
exact  systematic  position,  since  some  botanists  think  that  it  is 
more  closely  related  to  Phragmidium  than  to  Chrysomyxa 
(Melampsoropsis  of  Arthur).  The  writer  inclines  to  the 
Chrysomyxa  relationship,  since  the  telial  spores  are  thin-walled, 
colorless,  and  septate  like  those  of  Chrysomyxa,  and  the  uredinial 
stage  is  not  provided  with  paraphyses,  as  are  the  uredinia  of 
Phragmidia  on  Rubus  species.  Studies  were  made  to.  determine 
its  first  stage,  so  that  this  question  could  be  settled  more  definitely, 
but  unfortunately  the  results  were  not  conclusive.  If  closely 
related  to  Chrysomyxa,  the  I  stage  no  doubt  is  some  species  of 
Peridermium  {P.  Peckii,  for  instance),  while,  if  closely  related 
to  Phragmidium,  such  an  aecial  stage  is  improbable,  and 
might  be  supplied,  as  has  been  suggested,  by  Uredo  Muelleri. 
We  give  a  discussion  of  these  two  fungi  before  proceeding  to 
the  known  stages  of  the  Kuehneola. 

?  I.  Plate  XXIX,  a.  Peridermium  Peckii  Thm.  has  for  its 
host  Tsuga  canadensis,  and  is  apparently  confined  to  North 
America,  while  Kuehneola  alhida  has  a  much  wider  distribu- 
tion. The  Peridermium  occurs  on  the  under  side  of  the  leaves 
in  two  parallel  rows,  one  on  either  side  of  the  midrib,  and 
forms  slender,  white,  fragile  peridia  that  usually  split  into 
temporary  filaments  upon  their  dehiscence.  Ordinarily  this 
aecial  stage  does  not  occur  abundantly,  usually  only  one  infected 
leaf  showing  on  a  branchlet.  According  to  Arthur  and  Kern 
(5,  p.  434),  who  report  only  seven  collections,  P.  Peckii  has  so 
far  been  reported  only  from  the  Eastern  United  States.  The 
writer  has  found  this  species,  while  not  usually  abundant,  still 
not  uncommon  in  Connecticut,  the  following  specimens  having 
been  collected  here:  Coventry  Lake,  July  20,  1907;  Stafford 
Springs,  July  31,  1907;  Storrs,  July  22,  1907;  Union,  Aug.  i, 
1907;  Westville,  July,  1888  (Thaxter),  July  12,  27  and  28,  Aug. 
4,  1907.  In  some  of  these  collections  only  a  very  few  infected 
leaves  were  found,  but  at  Storrs  the  fungus  was  very  common 


384       CONNECTICUT    EXPERIMENT    STATION    REPORT^    I907-I908. 

on  certain  trees.  In  practically  all  of  the  cases  the  leaves  near 
the  ground  were  the  ones  infected,  but  on  one  very  badly  infested 
tree  the  fungus  was  found  as  high  as  twenty  feet  from  the 
ground. 

As  soon  as  this  Peridermium  was  found  a  search  was  com- 
menced for  the  stages  on  the  alternate  host,  but  without  find- 
ing anything  suspicious  until  at  Storrs  the  swamp  blackberry 
(Rubus  hispidus),  underneath  abundantly  infected  hemlock  trees, 
was  found  infested  with  Kuehneola  albida.  Examples  were  seen 
here  where  the  two  hosts  almost  touched  each  other,  each 
infected  with  its  fungus,  and  in  general  the  swamp  blackberry 
had  its  rust  only  when  situated  beneath  infected  hemlock  trees. 
A  few  days  later,  at  Stafford  Springs,  another  case  was  found 
where  infected  leaves  of  the  hemlock  were  close  to  rusted  leaves 
of  the  swamp  blackberry,  while  other  specimens  of  the  blackberry 
further  away  were  free.  As  no  other  rust  was  at  any  time  found 
so  situated  as  to  suggest  a  probable  relationship,  the  writer 
became  convinced  of  the  connection  of  these  two. 

Infection  experiments  in  the  greenhouse,  using  spores  from 
this  Peridermium  on  leaves  of  Ruhus  hispidus,  were  tried  on 
three  different  occasions,  but  no  infection  resulted,  except  pos- 
sibly in  one  case  when  one  sorus  of  the  II  stage  of  this  Kuehneola 
appeared  about  sixteen  days  afterward.  As  the  plants  used  were 
recently  transplanted,  most  of  the  leaves  finally  dropping  off, 
this  might  explain  the  failure  to  infect  the  host;  but  on  the  other 
hand,  as  the  plants  came  from  an  infected  region,  though  from 
a  spot  apparently  free  from  the  rust,  the  single  sorus  that  finally 
developed  may  not  have  come  from  the  spores  used,  but  from 
a  previous  outdoor  infection. 

The  most  unfavorable  point  against  the  relationship  of  Peri- 
dermium Peckii  and  Kuehneola  albida,  however,  is  that  with  this 
Peridermium  on  the  hemlock  leaves  there  occurs  a  pycnial  stage, 
while  with  the  Kuehneola  on  the  Rubus  host  there  is  sometimes 
found  a  uredinial  stage  known  as  Uredo  Muelleri  also  having 
pycnia.  This  Uredo  is  believed  by  some,  though  its  exact  rela- 
tionship apparently  has  never  been  proved  by  cultures,  to  be 
merely  the  primary  uredinium  (IP)  of  the  Kuehneola.  If  it 
really  is,  then  the  Peridermium  probably  has  no  relationship  to 
the  Kuehneola,  since  no  rust  is  known  that  has  pycnia  connected 
with  more  than  one  of  its  stasres.     From  these  considerations  it 


HETEROECIOUS    RUSTS.  305 

readily  appears  that  further  infection  experiments  are  necessary 
to  determine  the  relationship,  if  any,  of  Peridermium  Peckii, 
Uredo  Muelleri,  and  Kuehneola  albida.  Farlow  (lo,  p.  y2)  has 
also  suggested  a  possible  relationship  of  P.  Peckii  to  Calyptospora 
Goeppertiana;  and  it  is  barely  possible,  though  not  likely,  that  it 
is  connected  with  the  Necium  discussed  later. 

ir.  Plate  XXIX,  b.  Uredo  Muelleri  Schroet.  differs  from 
the  II  stage  of  Kuehneola  albida  in  having  its  sori  in  groups 
usually  on  the  upper  side  of  the  leaves,  a  few  large  uredinia  and 
pycnia  occurring  together  there,  while  the  smaller  uredinia  of 
Kuehneola  occur  scattered  on  the  under  side  of  the  leaves  and 
without  pycnia.  Mueller,  who  first  described  the  species  as 
Uredo  aecidioides,  according  to  Schroeter  (Krypt.  Fl.  Schl.  IIP: 
375)  thought  that  it  might  possibly  be  the  aecial  stage  of 
Chrysoniyxa  albida,  since  both  were  found  together.  That  they 
have  some  relationship  is  further  indicated  by  the  fact  that  not 
only  have  they  been  found  together  in  Europe  and  also  in 
America,  but  on  several  different  species  of  Rubus.  In  the  speci- 
mens collected  in  Connecticut  on  Rubus  hispidus,  both  at  Storrs 
and  Stafford  Springs,  this  Uredo  occurred  on  the  same  plants 
with  the  II  and  III  stages  of  Kuehneola  albida.  The  two  have 
also  been  found  elsewhere  in  New  England  associated  on  this 
same  host.  Dietel  (Hedw.  44:  122.  1905)  has  recently  sug- 
gested that  Uredo  Muelleri,  instead  of  being  the  aecial  stage  of 
Kuehneola  albida,  is  a  primary  uredinial  stage  of  it  that  merely 
functions  as  the  aecial  stage. 

II,  III.  Plate  XXIX,  c.  The  II  or  uredinial  stage  of 
Kuehneola  albida  is  the  more  common  and  injurious  of  these 
two  stages.  It  has  been  reported  on  several  species  of  Rubus 
from  the  United  States,  and  extends  over  a  wide  district.  While 
not  a  very  common  fungus,  when  it  does  occur  it  is  often  abun- 
dant. The  sori  are  very  small,  and  show  as  yellowish  circular 
outbreaks  scattered  over  the  under  side  of  the  leaves.  The  telial 
sori  often  occur  on  the  same  leaves  with  these,  but  are  easily 
distinguished  by  their  white  color.  The  telial  spores  found  here 
last  summer  had  all  germinated  before  the  middle  of  July.  In 
the  specimens  first  found  on  the  swamp  blackberry  both  of  these 
stages  occurred  on  the  old  leaves  (the  III  being  limited  to  these) 
that  had  lived  over  the  winter,  and  as  we  have  also  found  the 
II  stage  as  late  as  November  30th,  we  have  no  doubt  but  that  on 
28 


386       CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

this  host  the  fungus  carries  over  the  winter  through  the  uredinial 
stage,  and  so  the  I  stage  is  not  essential  for  its  appearence  the 
next  year.  The  collections  so  far  made  in  this  state  are  as  fol- 
lows :  Ruhus  hispidus,  Storrs,  II  and  III,  July  22,  II,  Oct. 
18,  1907;  Stafford  Springs,  II  and  III,  July  31,  1907;  West- 
ville,  II,  Nov.  30,  1907;  Ruhus  villosus,  Storrs,  II,  July  23, 
II,  Sept.  30,  1907. 

6.  Melampsoridium  Betulae  (Sclium.)  Arth. 
Plate  XXXI,  b.  (From  a  specimen  in  Seym.  Econ.  Fungi 
2^ij  b).  This  is  a  fungus  that  is  not  very  often  collected  in  the 
United  States,  but  apparently  occurs  as  frequently  in  New  Eng- 
land as  anywhere.  Though  careful  search  was  made  for  it  in 
Connecticut  the  past  season,  it  was  not  found.  The  writer,  how- 
ever, is  indebted  to  Professor  Farlow  for  specimens  collected 
on  September  20,  1890,  by  Setchell  at  Norwich,  on  Betula  populi- 
folia.  Only  the  II  stage  occurs  on  these.  While  both  the  II  and 
III  stages  have  been  found  in  the  United  States,  the  I  stage  has 
never  been  seen  here.  According  to  Klebahn  (Zeitschr.  Pflan- 
zenkr.  g:  18.  1899)  this  stage  occurs  on  the  leaves  of  Larix,  and 
has  been  found  in  several  places  in  Europe.  A  careful  search  for 
this  [Peridermium  Laricis  (Kleb.)  Arth.  and  Kern]  on  wild  and 
cultivated  larches  in  this  state  last  year  gave  no  evidence  of  its 
presence.  Just  how  the  fungus  passes  the  winter  in  this  country 
and  reappears  on  the  Betulae  is  unknown.  As  the  leaves  of  the 
Betulae  do  not  survive  the  winter,  reinfection  from  the  II  stage 
on  them  is  not  probable.  Though  not  known,  possibly  the 
uredinia  sometimes  occur  on  the  young  twigs,  and  by  this  means 
carry  over  the  fimgus. 

7.  Melampsoropsis  Cassandrae  (Pk.  &  Clint.)  Arth. 
(I.  Peridermium  consimile  Arth.  &  Kern.) 
I.  Plate  XXX,  a.  The  writer  (7)  has  recently  shown  the 
relationship  of  Peridermium  consimile  on  Picea  nigra  to 
Melampsoropsis  Cassandrae  on  Cassandra  calyculata.  Both  of 
these  fungi  were  found  in  Connecticut  for  the  first  time  last  year. 
The  only  locality  in  which  the  Periderm.ium  was  found  was  in 
a  spruce  swamp  along  the  railroad  just  beyond  West  Willing- 
ton  toward  Stafford  Springs.     When  first  seen  there  on  July  31st, 


HETEROECIOUS    RUSTS.  387 

the  aecia  were  just  beginning  to  shed  their  spores,  and  when 
seen  again  on  September  28th,  they  were  far  beyond  their  prime. 
The  aecia  occur  irregularly  in  one  or  two  rows  on  the  leaves, 
usually  four  to  eight  on  each  leaf.  The  infected  leaves  are  dis- 
colored yellowish,  and  look  as  if  they  would  be  shed  prematurely, 
but  there  is  no  indication  of  a  witches'  broom  formation.  The 
peridia,  as  shown  in  the  illustration,  are  somewhat  flattened,  and 
about  as  long  as  high.  They  break  open  irregularly  at  the  top 
to  shed  the  orange-colored  spores,  and  then  gradually  wear  away. 
A  striking  feature  of  this  species  is  the  very  conspicuous  reddish- 
brown  pycnia,  which  show  plainly  in  the  illustration  as  the  small 
black  specks. 

The  only  rust  suitable  for  the  alternate  stages  found  in  the 
vicinity  of  this  Peridermium  during  the  season  was  the  II  stage 
of  Melampsoropsis  Cassandrae  on  the  leather  leaf  under  the 
infected  spruce  trees.  Specimens  of  the  leather  leaf  from  the 
edge  of  the  swamp,  away  from  the  infected  spruces,  were  col- 
lected and  transplanted  in  crocks  in  the  greenhouse.  These 
were  watched  carefully,  and  two  or  three  plants,  upon  which  a 
sorus  or  two  of  the  Melampsoropsis  appeared,  were  discarded. 
Other  specimens  apparently  entirely  free  from  the  rust  were 
inoculated  with  the  spores  of  the  Peridermium,  and  about  six- 
teen days  later  the  uredinial  sori  appeared  on  a  number  of  the 
plants.  This  experiment  was  repeated  a  short  time  later,  using 
spores  from  leaves  for  a  short  time  in  a  damp  chamber,  and  the 
infection  took  place  in  this  case  in  about  eight  days.  Infection 
experiments  with  the  spores  on  Rubus  hispidus  and  Pyrola 
elliptica  failed  to  produce  anything.  While  necessity  compelled 
the  use  of  Cassandra  calyculata  from  the  infected  locality,  the 
results  indicated  that  the  sori  obtained  came  from  the  Perider- 
mium spores  used  in  the  experiments.  It  is  hoped,  however,  to 
repeat  the  inoculations  again  the  coming  year  with  plants 
entirely  above  suspicion. 

II.  Plate  XXX,  b.  The  uredinia  occur  as  minute  orange- 
yellow  dusty  outbreaks  on  the  under  side  of  the  leaves.  So  far 
we  have  been  unable  to  find  any  suggestion  of  the  telial  stage  on 
this  host,  though  a  careful  search  was  made  for  it  during  July, 
September,  October,  January  and  February.*  Arthur  describes 
this  stage,  but  apparently  from  other  hosts.  Last  October  the 
II  stage  was  found  on  the  leather  leaf  in  Beaver  Swamp,  at 

*See  addenda,  p.  396. 


388       CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

Westville,  and  as  no  spruce  trees  are  anywhere  near,  there  is  no 
doubt  that  the  fungus  can  survive  without  the  aid  of  the  aecial 
stage.  In  January  a  careful  examination  of  the  plants  in  this 
locality  was  made,  and  a  few  old  uredinia  were  found  on  the 
living  leaves,  which  largely  remain  on  the  plants  over  the  winter. 
Some  of  the  branches,  after  the  infected  leaves  were  removed, 
were  placed  under  a  bell  jar  indoors,  and  a  few  new  uredinia 
soon  appeared,  no  doubt  from  nearly  matured  sori.  No  others 
showing  during  the  next  week,  the  branches  were  left  undis- 
turbed for  about  a  month,  when  an  examination  revealed  several 
hundred  uredinia  present.  These  observations  show  that  the 
fungus  can  pass  the  winter,  on  the  old  but  living  leaves  that 
adhere  to  the  plants,  through  the  more  or  less  matured  uredinia, 
or  no  doubt  in  some  cases,  when  infection  takes  place  late  in  the 
season,  through  localized  mycelia  which  gives  rise  to  the  uredinia 
in  the  spring. 

8.  Melampsoropsis  Pyrolae  (DC.)  Arth. 
Plate  XXXI,  a.  This  is  commonly  known  as  Chrysomyxa 
Pyrolae,  and  occurs  in  the  United  States  chiefly  in  the  North- 
eastern States  and  the  Rocky  Mountains  on  various  species  of 
Pyrola.  So  far  in  this  state  only  the  II  stage  has  been  found, 
and  this  is  striking  when  once  detected,  since  the  under  surface 
of  the  infected  leaves  is  thickly  covered  with  brightly  colored 
uredinia.  The  collections  for  this  state  are  as  follows :  Pyrola 
elliptica,  Storrs,  May,  1904  (Graff)  ;  Pyrola  rotundifolia,  Pine 
Rock  in  Westville,  May,  1894  (Sturgis,  Fungi,  Col.  18 14)  ;  West 
Rock,  1902  (Clinton);  Vernon,  May  25,  1907  (Weatherby). 
No  aecial  stage  has  yet  been  discovered  for  this  species. 
According  to  Arthur  and  Kern  (5,  p.  432),  Rostrup  has  sug- 
gested that  P eridermium  conorum-Piceae  (Reess)  Arthur  and 
Kern  may  have  this  connection,  since  both  are  found  in  some- 
what the  same  localities  in  Europe  and  America.  A  search  for 
this  Peridermium  failed  to  reveal  its  presence  in  Connecticut, 
though  possibly  it  occurs  in  the  northwestern  part  of  the  state 
since  it  has  been  found  in  New  York  and  Northern  New  Eng- 
land. Apparently  the  aecial  stage  is  not  necessary  for  the 
appearance  of  the  rust,  as  the  leaves  of  the  Pyrolae  frequently 
live  over  the  winter  and  could  easily  carry  over  the  uredinial 
stage. 


HETEROECIOUS    RUSTS.  389 

9.     Necium  Farlowii  Arth. 

This  species,  found  on  hemlock,  Tsuga  canadensis,  has  recently 
been  made  the  type  of  a  new  genus  by  Arthur  (2,  p.  114),  who 
bases  his  description  on  material  furnished  by  Farlow,  and  col- 
lected by  Seymour  at  Chebacco  Lake,  Mass.,  and  by  Farlow  at 
Lake  Sunapee,  N.  H.  Arthur  describes  only  the  telial  stage,  and 
characterizes  the  genus  as  having  only  telia  and  possibly  pycnia. 
He  neglects  to  state,  however,  that  Seymour  collected  at  the 
same  time,  and  possibly  on  the  same  trees,  a  species  of  Caeomia 
which  might  very  well  be  the  aecium  of  this  fungus.  Farlow 
(9)  was  the  first  to  call  attention  to  these  fungi.  He  says : — 
"Besides  our  common  Chrysomyxa  on  Pyrola,  a  species  was 
found  on  Abies  Canadensis  at  Chebacco  Lake,  Essex  Co.,  Mass., 
by  Mr.  A.  B.  Seymour,  in  June,  1883.  This  is  probably  the  same 
as  Chrysomyxa  Abietis  of  Europe,  although,  as  the  spores  were 
not  quite  ripe,  one  cannot  be  certain.  If  there  is  a  difference, 
it  is  to  be  found  in  the  fact  that  the  teleutospores  are  arranged 
in  threads,  which  branch  less  than  the  European  forms.  But  at 
a  later  stage  of  development,  this  supposed  difference  might 
disappear.  At  the  same  time  and  place  Mr.  Seymour  found 
another  interesting  species  of  Urediniae,  also  on  Abies  Canaden- 
sis, not  on  the  same  branches  as  the  species  last  mentioned,  nor  on 
the  same  trees,  as  far  as  can  now  be  ascertained.  Sper- 
magonia  were  abundant  on  both  sides  of  the  leaves,  on  whose 
under  surface  were  elliptical  or  elongated  sori  of  a  pale  yellow 
color,  arranged  in  two  rows  parallel  to  the  midrib.  The  spores 
were  globose,  or  somewhat  elliptical,  about  13-17 /a  in  length, 
and  appeared  to  be  borne  in  chains,  composed  of  a  small  number 
of  spores.  It  is  possible  that  this  form  is  Caeoma  Abietis-pec- 
tinatae  Reess,  of  which  I  have  seen  no  specimens.  From  the 
description  of  Reess,  however,  this  species  has  larger  spores  than 
ours,  and  no  mention  is  made  of  spermagonia.  It  may  be  well 
to  designate  our  form  under  the  name  Caeoma  Abietis-Cana- 
densis  until  more  exact  information  can  be  obtained." 

The  writer  is  indebted  to  Professor  Thaxter  for  a  specimen 
of  this  Necium  collected  by  him  on  the  cones  of  hemlock  at 
Hamden,  Conn.,  July  18,  1889,  and  for  another  on  the  branches 
and  leaves  from  North  Carolina.  While  these  specimens  show 
only  the  telium,  Thaxter  wrote  on  the  label  of  the  Hamden 
specimen,    "teleutospores  of  Caeoma  on  hemlock  cones,"    and  in 


39°      CONNECTICUT   EXPERIMENT    STATION    REPORT,    I907-I908. 

a  letter  written  to  Professor  Farlow,  July  12,  1890,  said:  "I 
sent  you  yesterday  fresh  cones  with  mature  teleutospores,  one 
having  both  Caeoma  and  teleuto  forms  side  by  side.  I  found  a 
quantity  of  material  at  New  Hartford,  Conn.,  but  a  careful 
examination  of  the  leaves  on  branches  where  the  infected  cones 
were  hanging  by  dozens  revealed  nothing.  The  'Chrysomyxa' 
which  I  formerly  sent  you  from  North  Carolina  on  the  same  host 
occurred  only  on  young  shoots,  running  from  them  into  the 
leaves.  Though  very  common  in  North  Carolina,  I  did  not  find 
it  on  the  leaves  of  any  but  affected  shoots.  I  find  nothing  of 
the  sort  here,  though  I  have  looked  for  these  affected  shoots, 
which  are  conspicuous.  I  have  found  the  Caeoma  on  shoots,  of 
which  I  sent  you  a  specimen,  twice  only."  The  writer  has  never 
collected  this  Necium  in  Connecticut,  though  Thaxter  found  it 
not  uncommon  at  the  time  of  his  collections,  but  has  seen  a 
specimen  of  Caeoma  Abietis-canadensis  found  by  Dr.  Britton 
very  sparingly  in  June,  1906,  on  hemlock  leaves  in  Westville. 

Arthur  describes  the  Necium  as  occurring  on  the  leaves,  while 
Thaxter's  specimens  show  the  telia  on  the  cones  and  young  stems 
as  well,  thus  indicating  that  it  is  sometimes  perennial.  On  the 
cones  and  twigs,  at  least,  the  spores  seem  to  originate  beneath 
the  epidermal  cells  instead  of  in  them,  as  stated  by  Arthur.  The 
sori  on  these  parts  are  also  often  crowded  together  so  that  the 
spores  from  a  continuous  layer  (especially  on  the  cone  scales), 
across  the  entire  microscopic  section.  (Plate  XXXII,  5.)  This 
gives  them  the  general  appearance  ®f  being  an  epidermal  layer 
of  the  plant  tissues,  though  they  are  quite  unlike  the  true  epi- 
dermal cells.  The  sori,  where  distinct,  range  from  60 — 120  /u. 
in  depth  by  70 — 300  in  length.  The  simple,  slightly  tinted 
oblong  spores  are  very  closely  compacted  together,  so  that  in 
mature  sori  they  are  narrower  and  more  elongated  than  in  the 
immature.  Frequently  they  are  slightly  broader  and  more  deeply 
tinted  at  the  apical  end,  and  very  rarely  have  a  septum  above 
their  base.  They  seem  to  be  somewhat  larger  than  those  on  the 
leaves,  as  given  by  Arthur,  since  they  vary  from  40 — 85  /j.  in 
length  by  6 — 14 /j-  in  width,  the  shorter  and  broader  often  being 
immature.  They  arise  from  septate  basal  cells  of  about  equal 
diameter,  which  in  turn  develop  from  the  mycelial  threads  that 
ramify  through  the  plant  tissues  beneath.  In  sections  of  the  stem 
the  mycelium  shows  ver}^  abundantly  and  no  doubt  is  responsible 


HETEROECIOUS    RUSTS.  391 

for  the.  distortion  of  the  young  stems,  which  are  slightly  swollen 
and  sometimes  more  or  less  curved.  The  fungus  gives  a  reddish 
tinge  to  both  the  infected  stems  and  cones,  due  to  the  superficial 
colored  sori. 

While  not  exactly  like  Chrysomyxa  Ahietis,  which  has  septate 
spores,  and  even  less  like  Calyptospora  Goeppertiana,  this  species 
has  perhaps  more  the  characters  of  the  Melampsora-like  genera, 
so  everything  considered,  it  will  perhaps  rest  easiest  for  the  time 
being  in  the  new  genus  created  for  it  by  Arthur.  While  there  is 
no  positive  proof  that  Caeoma  Abietis-canadensis  has  any  con- 
nection with  the  Necium,  the  fact  that  a  Caeoma  has  been  found 
on  the  leaves,  cones  and  stems,  and  in  some  cases  associated 
with  the  Necium,  very  strongly  indicates  a  relationship.  If  this 
is  so,  or  if  Arthur  is  correct  in  believing  that  the  Necium  has  no 
other  stage,  of  course  the  fungus  does  not  really  come  within 
the  limits  of  this  article.  It  is  included  here  because  of  the 
possibility  that  it  may  have  for  its  aecial  stage  some  species  of 
Peridermium.  For  example,  Peridermium  Peckii  occurs  on  the 
same  host,  and  there  is  a  bare  possibility  that  the  two  are  con- 
nected, since  Professor  Farlow  writes  that  he  found  them  near 
together  at  Lake  Sunapee. 

ID.  Pucciniastruni  Agrimoniae  (Schw.)  Tranz. 
Plate  XXXI,  c.  So  far  no  aecial  stage  has  been  found  for 
this  fungus,  which  in  its  uredinial  stage  is  rather  common  in 
Europe  and  America.  Presumably  if  it  possesses  an  aecial  stage, 
this  is  one  of  the  Peridermia  since,  where  known,  species  of 
this  genus  have  such  connection.  The  uredinia  occur  on  the 
under  side  of  the  leaves  of  various  species  of  Agrimonia,  forming 
numerous,  scattered,  pale-orange  or  yellow,  minute  outbreaks, 
as  shown  in  the  illustration.  The  uredinia  of  this  genus  have  a 
rather  definite  peridium,  which  opens  by  a  pore,  guarded  by 
more  or  less  differentiated  neck  cells.  In  this  species  the  peridia 
are  not  sunken  very  deeply  in  the  tissues,  and  are  held  in  place  by 
the  overlapping  epidermis.  In  general  they  are  lenticular  to  sub- 
circular  in  cross  section,  and  vary  from  90 — iSoju.  in  height  by 
160 — 360  fx  in  width.  The  neck  cells  are  somewhat  differentiated, 
but  are  not  nearly  so  characteristic  as  in  some  of  the  other  species 
(P.  arcticiim  americanum,  see  Plate  XXXII,  3),  being  somewhat 
larger,  thicker  walled,  and  more  spore-like  in  appearance  than  the 


392       CONNECTICUT   EXPERIMENT    STATION    REPORT^    I907-I908. 

Other  peridial  cells,  which  are  frequently  rather  indistinct  and 
semi-gelatinized.  The  spores  are  rather  sparsely  covered  with 
inconspicuous  echinulations,  vary  from  ovoid  to  subspherical, 
occasionally  flattened  or  more  irregular,  and  are  15 — 20  /x,  rarely 
24  /A,  in  length. 

The  telia  of  this  fungus  were  first  described  by  Dietel  (Hedw. 
29:  152)  in  1890,  but  are  not  commonly  recognized,  probably 
because  they  develop  late  in  the  season,  and  in  the  specimens  we 
have  collected  do  not  show  to  the  naked  eye.  In  cross  sections 
of  the  leaf  of  one  of  the  collections  made  on  October  17,  this 
stage  was  shown  to  be  present.  The  sori  occurred  beneath  the 
epidermal  cells,  and  were  characteristic  of  true  Pucciniastrum 
telia;  that  is,  in  cross  section  the  spores  showed  as  twin  cells, 
but  when  viewed  from  above,  as  four  cells  firmly  bound  together 
(see  illustration,  Plate  XXXII,  4).  Where  the  sori  are  abundant, 
the  individuality  of  the  cells  is  almost  entirely  lost  by  being 
crowded  together.  The  compound  spores  vary  from  oval  to  sub- 
spherical,  and  are  about  19 — 28  ju.  in  length. 

11.  Pucciniastrum  minimum  (Schw.)  Arth. 
Neither  the  aecial  or  telial  stage  is  known  for  this  fungus 

according  to  Arthur.  We  found  its  uredinal  stage  on  cultivated 
Azalea  sp.,  August  14th,  1902,  in  a  Westville  nursery,  where 
it  was  very  abundant.  No  clue  was  obtained  to  its  other  stages, 
and  as  these  plants  were  soon  disposed  of,  it  has  not  been  seen 
since.  The  aecia  show  as  very  minute  orange-yellow  out- 
breaks on  the  under  side  of  the  leaves.  The  peridia  are  slightly 
imbedded  in  the  tissues,  are  hemispherical  to  conical  flattened, 
and  about  70 — 85  ju,  high  by  140 — 180 /a  wide.  The  neck  cells 
are  thick-walled,  and  not  especially  marked  or  prominent.  The 
spores  are  ellipsoidal  or  occasionally  more  elongate,  minutely 
echinulate,  and  16 — 25/1*  in  length. 

12.  Pucciniastrum  pustulatum   (Pers.)    Diet. 

In  Europe  the  above  species  has  been  connected  by  Klebahn 
(Zeitschr.  Pflanzenkr.  9:  22-6.  1899)  with  a  Peridermium  on 
Abies  pectinata,  but  so  far  the  aecial  stage  has  not  been  found 
in  this  country.  Possibly  Peridermium  balsameum  Pk.,  a  related 
species  on  Abies  balsamea,  is  this  stage,  though  according  to 
Farlow   (10,  p.  20)   it  has  been  conjectured  that  this  Perider- 


HETEROECIOUS    RUSTS.  393 

mium  belongs  to  the  American  species  of  the  Calyptospora  on 
Vaccinia.  Blakeslee  sent  the  writer,  in  August,  1907,  Perider- 
mmm  balsameum  from  the  Adirondacks,  where  the  only  suspi- 
cious alternate  forms  found  were  the  II  and  III  stages  of  Puc- 
ciniastrum  arcticum  var.  americanum  Farl.  on  Rubus  strigosus. 
(Described  in  Rhodora  10:13.  Ja.  1908.)  Thus,  while  the 
specific  ties  of  this  Peridermium  are  doubtful,  it  seems  certain 
that  it  is  connected  with  some  Pucciniastrum  (in  the  wide  sense, 
including  Calyptospora). 

The  II  and  III  stages  of  Pucciniastrum  pustulatum  occur  on 
various  species  of  Epilobium  scattered  over  the  United  States. 
Only  one  collection,  and  then  only  of  the  II  stage,  has  been  made  _ 
in  this  state,  on  Epilobium  sp.,  at  Hartford,  Oct.  20th,  1902. 
The  peridia  seem  to  be  composed  of  plant  and  fungous  cells,  and 
are  hemispherical  or  decidedly  flattened,  slightly  immersed  in 
the  tissues,  and  about  45 — 115  /j.  high  by  165 — 300 /a  wide.  The 
neck  cells,  while  somewhat  more  prominent  than  the  other  peri- 
dial  cells,  have  no  especial  markings,  and  seem  to  be  rather 
fugacious. 

13.  Pucciniastrum  Pyrolae  (Pers.)  Diet. 
This  is  another  species  of  Pucciniastrum  widely  distributed 
over  the  United  States,  whose  aecial  stage  is  unknown,  but 
which,  like  the  others,  is  supposed  to  be  a  Peridermium.  The 
only  specimens  collected  in  this  state  were  of  the  II  stage,  found 
at  Storrs,  July  24,  1907,  on  Pyrola  elliptica.  This  is  a  much  less 
conspicuous  fungus  than  the  Melampsoropsis  Pyrolae  which 
occurs  here  on  the  same  host.  Apparently  the  fungus  carries 
over  the  winter  through  the  uredinia  on  infected  leaves.  While 
no  clue  to  its  aecial  stage  was  obtained,  it  is  not  likely  to  be  either 
Peridermium  Peckii  or  P.  balsameum,  since  infection  experi- 
ments with  these  species  on  this  host  failed  to  give  results. 

SPECIES  NOT  YET  REPORTED  BUT  PROBABLY  OCCURRING  IN   CONN. 

The  following  species  have  not  yet  been  found  in  this  state, 
but  very  probably  will  be  collected  here  sometime  as  they  have 
been  Hsted  from  adjacent  states. 

I.  Calyptospora  columnaris  (Alb.  &  Schw.)  Kuehn  (C.  Goep- 
pertiana)  on  Vaccinium  sps.  (I.  Peridermium  columnar e 
(Alb.   &   Schw.)    Schm.   &   Kze.   on  Abies   sps.      Not  yet 


394      CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

reported  in  America.  Peridermium  Peckii  and  P.  balsameum 
have  been  suggested  as  possibly  belonging  to  this  Calyptos- 
pora.) 

2.  Coleosporium   Helianthi    (Schw.)    Arth.   on   Helianthus   sps. 

(Peridermium  unknown.) 

3.  Coleosporium  Senecionis  (Schum.)  Fr.  on  Senecio  sps.     (I. 

Peridermium  oblongisporium  Fckl.  on  leaves  of  Pinus 
sylvestris.     Not  yet  found  in  America.) 

4.  Cronartium  Comandrae  Pk.  on  Comandra  umhellata.     (Peri- 

dermium unknown.) 

5.  Cronartium  rihicola  Waldh.  on  Ribes  sps.  cult.     (I.  Perider- 

mium Strohi  Kleb.  on  branches  of  Pinus  Strobus.  Liable 
to  be  introduced  on  white  pine  imported  from  Europe.) 

6.  Melampsorella   elatina    (Alb.    &   Schw.)    Arth.    {M.    Caryo- 

phyllacearum)  on  Caryophyllaceae.  (I.  Peridermium  elati- 
num  Alb.  &  Schw.,  Schm.  &  Kze.  on  A^ies  balsamea.) 

7.  Pucciniastrum  arcticum  americanum.  Farl.  on  Rubus  strigo- 

sus.  See  PI.  XXXII,  3.  (Peridermium  unknown  but  pos- 
sibly P.  balsameum;   see  page  393.) 

8.  Pucciniastrum   Myrtilli    (Schum.)    Arth.    (P.    Vacciniorum) 

on  Gaylussacia  sps.  and  Vaccinium  sps.  (Peridermium 
unknown.) 

LITERATURE. 

The  following  are  a  few  of  the  American  references  relating 
to  our  Peridermia  and  their  probable  alternate  stages : 

1.  Arthur,  J.  C.     Peridermium  on  Pinus  rigida.    Joum.   Myc.   11:  52. 

Mr.  1905. 

Failed  to  infect  leaves  of  Lobelia  syphilitica  with  spores  of  above 
fungus. 

2.  Arthur,    J.    C.     Uredinales.     North    Amer.    Flora.    7:     85-123.     Mr. 

1907. 

Gives  within  these  pages  the  heteroecious  rusts  of  N.  A.  having 
Peridermia  for  their  aecial  stage,  describing  all  the  stages  so  far 
as  known. 

3.  Arthur,  J.  C.     Cronartium  Quercus  (Brond.)   Schroet.     Journ.  Myc. 

13:     194.     S.  1907. 

Produced  above  fungus  on  Quercus  velutina,  but  not  on  Q.  alba, 
by  using  spores  of  Peridermium  cerebrum  from  Pinus  virginiana. 

4.  Arthur,   J.    C.    Peridermium   pyriforme   and   its   probable   alternate 

host.     Rhodora  9:  194-5.     S.  1907. 

Suggests  from  observations  made  by  Dr.  Thorn  of  Conn.,  that 
the  above  is  the  aecial  stage  of  Cronartium  Comptoniae. 


HETEROECIOUS    RUSTS.  395 

5.  Arthur,  J,  C.  and  Kern,  F.  D,     North  American  species  of  Peri- 

dermium.     Bull.  Torr.  Bot.  Club  33:  403-38.     Au.  1906. 

Give  general  discussion,  keys,  descriptions,  synonyms,  hosts,  and 
distribution  of  thirty  species. 

6.  Clinton,   G.   P.     Peridermiwn   acicolum,  the  aecial  stage  of   Coleo- 

sporium  Solidaginis.     Science  25:  289-90.     F.   1907.     (Also  note  in 
Ann.  Rep.  Conn.  Agr.  Exp.  Stat.  1906:   320.     My.  1907.) 

Proves  by  observations  and  inoculation  experiments  the  rela- 
tionship of  the  above  rusts. 

7.  Clinton,  G.  P.     Notes  on  certain  rusts  with  special  reference  to  their 

Peridermial  stages.     Science  27:    340.     F.   1908. 

Proves  by  infection  experiments  the  relationships  of  Peridermium 
pyriforme  to  Cronartium  Comptoniae  and  P.  consimile  to  Melamp- 
soropsis  Cassandrae,  and  suggests  possible  relationship  of  P.  Peckii 
to  Chrysomyxa  albida. 

8.  Farlow,  W.  G.    Appalachia  3:  239-43.    Ja.  1884. 

Gives  notes  on  Peridermia  of  the  White  Mountains. 

9.  Farlow,  W.  G.     Notes   on  some,  species  of   Gymnosporangium  and 

Chrysomyxa  of  the  United   States.     Proc.   Amer.   Acad.  Arts   Sci. 
20:  322-3.     1885. 

Gives  notes  on  Chrysomyxa  Ledi,  II,  III,  and  Uredo  Ledicola,  on 
Ledum,  and  suggests  Peridermium  (probably  P.  Abietinum)  on 
Abies  nigra  may*  be  associated  with  former;  thinks  Aecidium 
pseudo-columnare  of  Kuehn  may  be  the  same  as  P.  balsameum  of 
Peck;  also  gives  notes  on  Chrysomyxa  Abietis  (?)  and  Caeoina 
A  bietis-Canadensis. 

10.  Farlow,  W.  G.     Aecidium  sps.     Bibl.  Ind.  N.  A.  F.     S.  1905. 

Gives  bibliography  of  the  species  of  Peridermium  (under  the  form 
genus  Aecidium)  with  notes  upon  the  following:  Aecidium  Abie- 
tinum (p.  13),  A.  balsameum  (p.  20),  A.  carneum  (p.  25),  A.  cere- 
brum (p.  2y),  A.  conorum-Piceae  (p.  35),  A.  decolorans  (p.  38), 
A.  deformans  (p.  39),  A.  elatinum  (p.  40),  A.  ornamentale  (p.  71), 
A.  Peckii  (p.  72),  A.  Pini  (p.  75). 

11.  Farlow,  W.  G.  and  Seymour,  A.  B.    Prov.  Host  Index  Fungi  U.  S. : 

158-170.     1891. 

List,  under  the  various  hosts,  species  of  Peridermia  that  have 
been  reported  for  the  U.  S. 

12.  Freeman,  E.  M.     Minnesota  Plant  Diseases:    275-7.     Jl-   1905. 

Gives  notes  on  pine  stem  rust,  leaf  rust  of  pines  (suggests  rela- 
tionship to  rusts  on  asters  and  goldenrod),  and  witches'  broom  of 
balsam  fir. 

13.  Kellerman,  W.  A.    Pine  rust,  Peridermium  Pini.    Journ.  Myc.  11:  32. 

Ja.  1905. 

Sowed  spores  of  "Peridermium  Pini"  obtained  from  Ohio  on 
Campanula  Americana  outdoors  and  produced  urediniospores,  thus 
proving  the  fungus  on  the  pine  to  be  the  aecial  stage  of  Cole- 
osporium  Campanulae. 


396  CONNECTICUT    EXPERIMENT    STATION    REPORT,    I907-I908. 

14.  Peck,   C.    H.    Perideriniuvi    pyrifonne    Pk.     Bull.    Torr.    Bot.    Club 

6:    13.     F.  1875. 

Describes  this  as  a  new  species  on  pine  branches,  probably  from 
Newfield,  N.  J. 

15.  Seymour,  A.  B.    Peridermium  Pini  Lev.  var.  acicolum  Wallr.     Eco. 

Fungi  223.     1893. 

States  that  this  species  on  Pinus  rigida  is  commonly  associated 
with  Cronartium  on  Myrica  asplenifolia. 

16.  -Shear,    C.    L.     Periderviiuni    cerebrum    Pk.    and    Cronartium    Quer- 

cuum  (Berk).    Journ.  Myc.  12:   89-92.     My.  1906. 

Gives  results  of  outdoor  inoculation  experiments  by  which  the 
Peridermium  is  shown  to  be  the  aecial  stage  of  the  Cronartium; 
gives  hosts  and  distribution  of  each. 

17.  Underwood,    L.   M.   and    Earle,    F.    S.    Notes    on   pine-inhabiting 

species  of  Peridermium.      Bull.  Torr.  Bot.  Club  23:  400-5.     O.  1896. 

Give  notes  on  three  species   from  Eastern  U.   S.,   and  mention 

three  others  from  the  western  part  which  they  have  not  examined. 


ADDENDA. 

(i)  See  Kuehneola  albida,  p.  383.  The  writer  is  indebted  to  Professor 
Farlow  for  calling  his  attention  to  an  infection  experiment  with  this 
rust  by  Ernest  Jacky,  published  in  the  Cent.  Bak.  Par.  Infek.  18:  91-3. 
February,  1907.  This  writer  claims  to  have  produced  Uredo  Muelleri  on 
Rubus  fruticosus  from  Phagmidium  [Kuehneola]  albidum  on  the  same 
host.  As  this  experiment  was  conducted  in  the  woods  merely  by  laying 
infected  leaves  on  the  plants,  and  as  these  leaves  came  from  plants  which 
also  contained  Uredo  Muelleri  at  that  time,  there  may  be  some  question 
about  his  conclusion.  In  a  late  more  careful  experiment,  using  Uredo 
Muelleri  he  produced  Uredo  Muelleri,  apparently  as  he  claims. 

(2)  See  Melampsoropsis  Cassandrae,  p.  386.  On  May  4,  1908,  just  as  this 
paper  was  going  to  press,  the  writer  succeeded  in  finding  the  III  stage  of 
the  above  fungus  on  Cassandra  calyculata,  at  Beaver  Swamp,  Westville, 
on  the  same  plants  that  the  II  stage  was  found  on  during  the  previous 
fall  and  winter.  The  sori  are  small,  about  one-eighth  of  an  inch  or  less 
in  diameter,  are  situated  on  the  under  surface  of  the  leaves  (though 
also  discoloring  the  upper  surface)  and  show  to  the  naked  eye  as  slightly 
elevated,  waxy,  chestnut-red  areas.  These  may  be  distinct  or  somewhat 
run  together,  and  under  a  hand  lens  seem  to  consist  of  more  minute 
divisions  really  caused  by  the  leaf  venations.  The  sori  at  this  time  were 
scarcely  mature,  but  undoubtedly  some  of  them  would  mature  very 
shortly.  Their  season,  apparently,  is  from  May  to  June,  which  is 
the  only  time  of  the  year  I  had  not  before  looked  for  this  fungus. 


PLATE  XVII. 


a.     Baldwin  Spot,  p.  340. 


b.     Spray  Injury,  p.  342. 


TROUBLES  OF  THE  APPLE. 


PLATE  XVIII. 


a.     Chestnut  Bark 
Disease,  p.  345. 


b.     Anthracnose  of  Currant,  p.  347. 


c.     Bitter  Rot  of  VViiite  Currants,  p.  347. 
FUNGI   OF   CHESTNUT  AND  CURRANT. 


PLATE  XIX. 


a.     On  young  Currant  shoot. 


b.     On  fruit  of  Gooseberry. 
POWDERY  MILDEW,  Spimcroihcca  iiiors-itvar,  p.  348. 


PLATE  XX. 


a.     Leaf  Scorch  of  Farleyense  Fern,  p.  349. 


b.      Rust  of  Juneberry,  p.  351. 
DISEASES  OF   FERN   AND  JUNEBERRY. 


PLATE  XXI. 


HERBARIUM 

CONN.    AGR. 

e:x 

.p.     STA 

•    l^ 

w 

^p     ^^^ 

• 

%    < 

^ 

9 

^3 

« 

9    # 

%. 

Q 

• 

# 

1       % 

# 

% 

*l 

a.     Sclerotia  from  the  soil.     X  2. 


b.     Artificial  cultures  on  corn  meal  and  agar. 
STEM    ROT   FUNGUS  OF   HERBACEOUS  PLANTS,  p.  351, 


PLATE  XXII. 


Healthy. 


Diseased. 


a.     Showing  effect  on  size  of  leaves. 


b.     Showing  injury  to  leaves.      X  2. 
BLIGHT  OF  WHITE   PINE,  p.  353. 


PLATE  XXIII. 


a.     Internal  Brown  Spot,  a 
physiological  trouble, 
p.  355. 


b-d.     Scurf,  caused  by  Spondylocladiinii  fungus,  p.  357. 
b. 


Surface  of  tubers  greatly  X . 


■•',>jjj?f  -■- 


c.     Spore  stage.  d.     Sclerotia. 

DISEASES  OF   POTATO  TUBERS. 


PLATE  XXIV. 


a.     Formalin.    (Plot  i] 


b.     *Steam.   (Plot  2) 


c.     Weak  formalin  sprinkled. 
(Plot  5) 


d.     Check,  no  treatment. 
(Plot  6) 


(♦Shortly  before  photographing,  the  best  plants  were  pulled,  so  this  should  really  show- 
somewhat  better  than  a.) 


TREATMENT  OF  TOBACCO   SEED  BEDS   FOR   ROOT   ROT,  p.  365. 


PLATE  XXV. 


a.     I  on  Pinus  rigida.     X  4. 


b.     II  on   Campanula  rapiinculoides.     X  2. 


4>-^<(^SC''^4>*4» 


c.     Ill  on  Cainpanula  rapiinculoides.     X  4. 


{Peridermiuni  Rosliiipi),   II,   III   STAGES  OF   Colfosporim/i  Caiiipa/iiilat',  p.  ^,74. 


PLATE  XXVI. 


a.     Showing  a  bunch  of  infected  leaves  natural  size.     I. 
O.  I. 


b.     O,  I  on  Finns  rigida.     X  8. 
0,  I  {Pei-ideruiiimt  acicoluin) ,   STAGES  OF   Coli-ospoiiinii  So/idai;iiiis,  p.  375. 


PLATE  XXVII. 


a.     II  on  Solidago  rugosa.     Natural  size  and  X  8. 


b.     Ill  on  Solidago  ntgosa.     X6. 
II,  III   STAGES  OF   Coleosporiioii  Solidaginis,  p.  377. 


PLATE  XXVIII. 


On  Pimis  sylvestris. 


"i^^B^H^r^^^  ^S^y^*^^ 

w^ 

Lj^S^„„-          i^^'^alF^^:::,^  '-^ 

\.  wK^^^m^^''  1 

^ 

^^^prlj^JNi^^^ 

p-^ 

*^hIO^^  ifflK*".  ^''^^"^ 

^^HbbBBhII^IIKi  "^^P*  ^^  --Jk 

a.     I  natural  size.  b.     1X2. 

On  Comptonia  asplenifolia . 


c.     II  X  4.  d.     Ill  X  4- 

{Peridermiujii  pyrifonne),   M,  III   STAGES  OF   Croiiar/ium  Ccnnp/oniae,  p.  3S0. 


PLATE  XXIX. 


a.     I  Peridennium  Peckii  on  Tsiiga  canadensis. 


b.     ir  Uredo  JMiielleri  on  Rubus  hispidus. 


c.     Ill  Kiteluieola  albida  on  Rubus  Iiispidus. 
ir,   111   STAGES   (X  4)  POSSIBLY  OF  THE  SAME   RUST,  p.  383. 


PLATE  XXX. 


a.     O,  I  on  Pice  a  nigra. 


b.     II  on  Cassandra  calyciilata. 
0,  I   {Peridcrmiuvi  consimile),  II   STAGES  (X  4)  OV  Mclauipsoropsis  Cassa)idrac,  p.  386. 


Melampsoropsis  Pyrolae,  p. 


PLATE  XXXI. 

3felainpsoridiuiJi  Betulae,  p.  386. 


a.     On  Pyrola  rotundifolia.      X  4. 


b.     On  Betula  puiiiila.     X  2. 


c.     Piicciniasfruui  Agrimouiae  on  Affriuioiiia  sp.,  p.  391.      X  2. 
II   STAGE   OF  THREE   HETEROECIOUS   RUSTS. 


PLATE  XXXII. 


a.  spores;  b.  germ  tubes;  c.  peridial  cells;  d.  peridium;  e.  neck  cells 
of  peridium;  f.  epidermal  cells  of  host;  g.  parenchymatous  cells  of  host; 
h.  mycelium;  i.  fertile  cells  of  mycelium,  i'""*  (i)  Peridet'iniiini  acicoluui; 
(2)  P.  pyriforme ;  (3)  P.  Peckii;  (4)  P.  consii)iile.  2'"'^  Germination  of  II 
spores  of  (i)  Coleosporiiim  Solidaginis  and  (2)  C.  Campanulae .  3.  Partial 
section  through  peridium  of  Pncciniastruni  arcticuui  var.  a)iiericanii}>i. 
4'^'^  Compound  spores,  III,  of  Piicciniastriim  Agrhnouiae,  shown  in  longi- 
tudinal (i)  and  cross  (2)  section.  5'  -  Cross  section  through  telia  of 
Neciuin  Farlowii  on  stem  (i)  and  on  cone  (2). 


I,  II,  III   SPORE   STAGES  OF   CERTAIN    RUSTS. 


,U  to 


>-  _?:>  X     i_%i    t,.t 'i.e** 

i\ 

i  f    '-- 

^  cl-in^etts 

A: 

ultural 

State  of  Connecticut 


REPORT 


OF 


The  Connecticut  Agricultural 
Experiment  Station 

REPORT  OF  THE  STATION  BOTANIST,  1908 

G.  P.  CLINTON,  SC.D. 

BEING  PART  XII  OF  THE  BIENNIAL  REPORT  OF  I907-I908 


CONNECTICUT 

AGRICULTURAL   EXPERIMENT 
STATION 


REPORT   OF  THE   BOTANIST 

G.  P,  CLINTON,  ScD, 


PAGE 

I.   Notes  on  Fungous  Diseases,  etc.,  for  1908, 849 

A.  General  Notes  on  Diseases  previously  reported,       .     .     .  849 

B.  New  Observations  on  Diseases  previously  reported,     .     .  853 

C.  Diseases  not  previously  reported, S58 

II.   Peach  Yellows  and  so-called  Yellows,        872 

III.  Chestnut  Bark  Disease,  Diaporthe parasitica  Murr.,      ....  879 

IV.  Artificial    Cultures   of    Phytophthora,  with    special   reference 

to  oospores, 891 


ISSUED  JULY,  1909 


PART  XII. 

REPORT  OF  THE  BOTANIST  FOR  1908. 

G.  P.  Clinton,  Sc.D. 


I.     NOTES  ON  FUNGOUS  DISEASES,  ETC.,  FOR  1908. 

A.      GENERAL  NOTES  ON  DISEASES  PREVIOUSLY  REPORTED. 

Weather  conditions.  The  winter  of  1907-08  was  on  the  whole 
rather  mild,  so  that  no  very  general  winter  injury  resulted  to  the 
shrijbs  and  trees.  During  the  latter  part  of  January  and  in 
February,  however,  the  cold  was  sufficient  to  kill  a  good  many 
of  the  peach  buds.  Likewise,  certain  peach  trees  suffered  some- 
what from  the  collar  girdle  injury,  which  is  described  elsewhere. 

The  spring  of  1908  was  one  of  the  earliest  and  driest  that  we 
have  had  in  some  years,  the  early  vegetables  being  a  week  or  two 
in  advance  of  the  average  year,  and  considerably  more  than  that 
as  compared  with  the  year  of  1907,  which  was  tmusually  late. 

The  summer,  like  that  of  1907,  was  unusually  dry,  but  differed 
in  that  the  drought  came  in  two  periods.  The  first  drought 
extended  into  the  middle  of  July.  The  latter  part  of  that  month 
and  most  of  August  were  sufficiently  moist  for  the  needs  of. 
vegetation  in  general ;  but  the  last  of  August  and  practically  all 
of  September  were  again  free  from  rains.  The  splitting  of  the 
drought  by  the  scattered  rains  during  midsummer  had  the  effect 
of  keeping  down  drought  injury  much  below  that  of  1907,  when 
the  dry  weather  lasted  from  June  until  August. 

While  the  drought  did  harm  to  certain  of  our  crops,  such  as 
alfalfa,  asparagus,  potatoes  and  celery,  on  the  other  hand,  some, 
like  the  peach,  muskmelon  and  tobacco,  were  in  the  end  benefited 
by  the  dry  weather,  especially  by  that  of  the  late  summer  and 
fall.  The  comparatively  dry  weather  of  the  growing  season  as 
a  whole  was  sufficient  to  keep  down  most  parasitic  fungi,  so  that 
1908,  like  the  past  few  years,  was  not  one  in  which  these  pests 
(with  a  few  exceptions)  did  any  great  injury  to  our  cultivated 
plants. 

60 


850        CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

The  fall  frosts  held  off  somewhat  later  than  usual,  the  first 
one  of  consequence  coming  on  October  12th,  the  slight  frost  of 
October  5th  merely  injuring  the  cucurbits. 

Market  garden  and  other  plants.  There  were  a  number  of 
complaints  of  the  premature  yellowing  and  dying  of  alfalfa 
plants,  these  being  affected  sometimes  in  spots.  While  we  did 
not  have  the  opportunity  of  examining  the  plants  in  the  fields, 
from  the  absence  of  any  sure  signs  of  fungous  or  insect  attack 
on  the  specimens  sent  to  the  station,  we  were  inclined  to  believe 
that  the  trouble  was  due  to  the  dry  weather.  Certain  weeds, 
such  as  the  pigweed,  often  showed  similar  injury,  due  to  the 
drought. 

While  the  rust  of  asparagus  was  more  common  than  usual,  it 
did  not  do  as  much  harm  as  the  drought.  Nearly  all  asparagus 
beds  suffered  from  the  dry  weather,  so  that  the  tops  were  fre- 
quently dead  early  in  September.  Such  injury  from  drought  is 
likely  to  show  itself  the  following  spring  in  a  lower  yield  of  tips. 

The  anthracnose  of  string  beans  was  conspicuous  by  its  absence 
this  year,  and  the  downy  mildew  of  the  Lima  beans  only  appeared 
at  the  very  end  of  the  season,  when  it  was  too  late  to  do  any 
harm. 

The  muskmelons  were  better  this  year  than  for  some  years 
past,  in  yield  and  especially  in  quality.  Connecticut  melons  on 
the  Boston  market  were  unusually  fine.  This  was  due  to  the 
warm,  dry  weather  which  is  so  essential  to  this  crop,  and  which 
also  helped  to  keep  down  its  fungous  enemies.  However,  during 
the  latter  part  of  the  season  many  of  the  vines  were  injured  or 
prematurely  killed  by  the  attacks  of  the  downy  mildew  and  the 
leaf  spot  blights. 

The  blight,  or  downy  mildew,  of  the  potato,  so  far  as  the  writer 
could  discover  from  a  careful  search  during  the  season,  did  not 
occur  at  all,  it  being  the  first  time  in  seven  years,  at  least,  that  it 
was  not  found.  This  meant  that  there  was  no  injury  by  rot  to 
the  tubers.  But  while  the  potatoes  escaped  the  blight,  due  to  the 
dry  season,  from  the  same  cause  they  suffered  unusually  from 
tip  burn,  so  that  practically  all  the  vines,  especially  of  the  late 
varieties,  were  prematurely  killed,  and  the  yield  very  greatly 
reduced.  In  some  fields  the  tubers  were  scarcely  marketable. 
There  was  some  scab,  it  being  reported  as  quite  bad  in  certain 
fields. 


NOTES    ON    FUNGOUS   DISEASES    FOR    I908.  85 1 

The  midsummer  rains  prevented  much  injury  resulting  from 
the  drought  to  the  tobacco  fields,  while  the  dry  spell  of  the  fall 
favored  its  harvest  and  curing  in  the  barns.  As  a  result  the 
tobacco  crop  was  unusually  good.  No  complaint  was  made  of 
serious  root  rot  in  the  seed  beds,  and,  so  far  as  we  have  heard, 
the  trouble  in  the  fields,  due  to  the  Thielavia  fungus  and  other 
causes,  was  not  especially  conspicuous  in  the  Suffield  region.  In 
some  fields  there  was  more  or  less  calico.  (Plate  LXVIb.) 
This  is  a  trouble  to  which  we  have  paid  especial  attention  during 
the  past  two  years,  and  we  expect  next  year  to  give  an  account 
of  these  investigations. 

Fruits  and  berries.  While  the  apple  crop  was  comparatively 
small  and  of  rather  poor  quality,  this  was  not  due  to  any  especial 
attacks  from  fungi.  By  far  the  most  conspicuous  apple  fungus 
of  the  year  was  the  leaf  rust  (Roestelia  pirata).  Conditions 
must  have  been  unusually  favorable  in  the  spring  for  its  spread 
from  the  "cedar  apples,"  its  winter  stage  on  the  red  cedars,  for 
it  occurred  on  apple  trees  in  some  cases  quite  distant  from  any 
cedars.  It  was  one  of  the  fungi  most  frequently  sent  in  for 
identification. 

The  peach  apparently  suffered  more  than  any  other  fruit  tree 
from  fungous  and  physiological  diseases  the  past  year.  While 
the  scab  and  brown  rot  were  less  noticeable  than  usual,  the  latter 
largely  because  of  the  favorable  dry  weather  at  harvest  time,  the 
bacterial  spot  was  more  common  than  at  any  time  since  we  first 
called  attention  to  it  in  1903.  There  was  also  considerable  injury 
from  collar  girdle  in  some  orchards.  Yellows  and  so-called 
yellows  were  very  prominent,  especially  in  certain  orchards. 
While  the  peach  crop  was  not  as  large  as  some  years,  the  quality 
was  above  the  average. 

With  the  quince,  as  with  the  apple,  rust  (Plate  LX  c)  was 
unusually  prevalent,  especially  in  the  vicinity  of  New  Britain. 
The  quince  rust  (Roestelia  aurantiaca),  however,  generally 
attacks  the  fruit  and  the  young  stems,  especially  the  fruit-spurs. 
Its  mycelium  in  the  stem,  so  far  as  we  have  been  able  to  learn, 
is  not  perennial,  so  that  infection  each  year  depends  upon  the 
"cedar  apple"  stage.  It  forms  elongated  but  quite  fragile  white 
peridia  that  rise  above  the  infected  parts  and  are  filled  with 
bright  orange-colored  spores.  The  half-tone  shows  a  quince  in 
which  these  peridia  have  worn  off. 


852         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

Among  the  diseases  of  the  small  fruits,  the  downy  mildew  of 
the  grape  and  the  yellows  of  raspberries  were  the  only  ones  to 
which  our  attention  was  called  as  being  unusually  common.  We 
also  noticed  one  case  of  leaf  spot  (Septoria  Ruhi)  of  raspberry 
which  was  as  bad  as  any  we  have  ever  seen  on  this  host. 

Forest  and  shade  trees.  Because  of  the  articles  that  have  been 
written  and  the  great  damage  it  has  caused,  the  chestnut  hark 
disease  is  now  attracting  much  more  attention  in  this  state  than 
it  has  before.  It  is  a  question  whether  this  trouble  is  on  the 
increase  or  whether  it  is  merely  being  reported  in  new  localities 
because  of  the  search  that  has  been  made  for  it.  We  treat  of 
it  more  at  length  in  a  special  paper  later  in  this  Report. 

The  fungus  most  frequently  sent  to  the  station  for  identifica- 
tion during  the  year  was  the  black  spot  (Rhyfisma  acerinum)  of 
the  maple,  and  our  own  observation  also  showed  that  it  was 
unusually  common.  This  fungus  is  conspicuous  because  of  the 
evident  black  spots,  something  like  finger  prints  (see  Plate 
LXIV  a),  that  develop  on  the  leaves.  These  are  slightly  elevated 
on  the  upper,  and  often  concave  on  the  lower  surface,  showing 
less  prominently  beneath.  So  far  as  known,  this  occurs  only  on 
the  leaves  and  does  not  mature  on  them  until  the  next  spring. 
The  evident  method  of  combating  it  is  to  rake  together  and  burn 
the  leaves  in  the  fall.  While  the  cultivated  cut-leaved  variety 
of  the  soft  maple  is  the  one  most  commonly  attacked,  we  have 
also  found  it  on  the  soft  and  red  maples. 

The  blight  of  white  pine,  which  attracted  so  much  attention 
last  year,  was  very  much  less  conspicuous  this  year  and  we 
received  no  complaints  of  it.  Of  course  last  year's  leaves  which 
were  killed  at  the  tips  still  showed  the  injury,  and  in  some  cases 
the  leaves  put  out  this  year  also  showed  the  trouble  somewhat. 
Early  in  the  spring  the  Forester  marked  all  of  the  injured  young 
trees  in  a  certain  block  at  the  state  plantation  at  Rainbow.  This 
block  will  be  watched  for  a  year  or  two  to  see  if  the  trouble 
spreads  and  what  its  effect  is  on  the  trees  already  diseased. 
When  examined  last  (fall,  1908),  the  trouble  seemed  not  to 
have  spread  (at  least  to  any  extent)  and  the  marked  trees  were 
improving,  the  leaves  put  out  this  year  being  usually  in  much 
better  shape  than  those  of  last  year.  The  results  so  far  seem  to 
confirm  our  statement  made  in  the  last  Report,  that  this  disease 
is  not  primarily  due  to  fungous  attack,  as  believed  by  some,  but 


NOTES    ON    FUNGOUS   DISEASES    FOR    I908.  853 

is    rather    the    result    of    adverse    weather    conditions    which 
culminated  in  the  drought  of  last  year. 

The  sycamore  trees,  which  were  severely  injured  last  year  by 
late  frosts  in  May,  just  as  the  leaves  were  appearing,  still  show 
the  effects  by  their  scantier  though  healthy  foliage.  Some 
writers  erroneously  attributed  this  injury  to  the  anthracnose. 


B.       NEW  OBSERVATIONS  ON  DISEASES  PREVIOUSLY  REPORTED. 

APPLE,  Pirtis  malus. 

Rust,  Gymnosporangium  macropus  Lk.  Plate  LX  a-b.  The 
aecial  stage  of  this  fungus  (Roestelia  pirata),  while  common  on 
apple  leaves,  has  not  before  been  reported  on  the  fruit  itself  in 
this  state.  In  the  fall  of  1907,  Mr.  A.  B.  Cook  sent  the  first 
specimen  that  we  have  seen.  The  past  year,  because  of  the  rust's 
imusual  abundance,  the  fruit  was  also  attacked  more  frequently 
than  usual.  On  a  roadside  seedling  near  Meriden,  in  September, 
we  found  it  quite  abundant  on  the  apples  as  well  as  on  the  leaves. 
The  peridia  on  the  fruit  varied  so  in  the  character  of  their  split- 
ting open  that  we  thought  possibly  both  of  the  species  of 
Roestelia  which  occur  here  were  present,  though  the  spores 
seemed  the  same.  Mr.  Kern,  however,  to  whom  we  sent  the  two 
specimens  shown  in  the  halftone,  pronounced  them  the  same. 

The  infected  apples  showed  a  progressive  development  of  the 
mycelium,  so  that  eventually  the  whole  apple  became  involved. 
Cutting  across  one  of  these  apples,  the  presence  of  the  mycelium 
was  shown  by  its  endochrome,  which  gave  an  orange  tint  to  the 
invaded  tissues.  This  infected  area  was  always  evident  at  the 
surface,  narrowing  down,  in  wedge  shape,  toward  the  core  in 
the  cross  section.  Another  peculiarity  that,  so  far  as  we  know, 
has  not  been  described  before,  was  the  development  of  immature 
pycnia  within  these  tissues ;  and,  in  the  seed  cavities  of  the  core, 
the  formation,  in  a  number  of  cases,  of  perfectly  mature  peridia. 

As  these  apples  offered  an  easy  method  of  obtaining  tissue 
containing  the  mycelium  of  the  fungus  free  from  other  germs, 
for  artificial  cultures,  attempts  were  made  to  grow  the  fungus  in 
this  way  on  apple  juice  agar,  but  in  none  of  the  cultures  did  the 
fungus  develop.  However,  so  far  none  of  the  rusts  have  been 
grown  in  such  artificial  cultures. 


854        CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

AZALEA,  Azalea  sps. 

Rust,  Pucciniastrum  minimum  (Schw.)  Arth.  In  the  Report 
of  the  station  for  1903,  p.  306,  we  reported  the  uredinial  stage 
of  this  fungus  under  the  name  Pucciniastrum  Vacciniorum  (Lk.) 
Diet.,  to  which  it  has  commonly  been  referred.  Arthur  in  N.  A. 
Flora  7^,  p.  109,  however,  considers  the  rust  on  Azalea  distinct 
from  that  on  Vaccinium,  and  describes  it  under  the  name  P. 
minimum,  but  states  that  the  telial  stage  has  never  been  reported. 
The  past  fall  we  again  found  this  rust  on  Azalea  nudiflora  (and 
apparently  other  cultivated  species)  in  the  local  nursery  where 
it  was  seen  before,  and  on  specimens  gathered  the  latter  part 
of  October  we  were  able  to  find  the  telial  stage.  The  sori  of  this 
stage  are  so  inconspicuous  that  it  is  necessary  to  cut  sections  of 
the  leaves  in  order  to  be  sure  of  the  presence  of  the  spores. 
These  compound  spores  are  of  the  normal  Pucciniastrum  type, 
showing  (when  not  too  much  crowded  together)  as  four  cells 
in  surface  view  and  two  cells  in  longitudinal  section.  They 
occur,  one  or  more,  in  the  epidermal  cells  of  the  upper  side  of 
the  leaves  above  the  uredinial  sori,  but  sometimes  appear  to  be 
situated  between  the  epidermal  cells  and  the  cuticle.  They  vary 
in  size  from  21  to  2^[i,  in  surface  view,  to  23  to  29/A  in  longi- 
tudinal section.  Their  walls  are  reddish-brown  in  color.  So 
far  nothing  is  known  of  the  aecial  stage  of  this  fungus,  which 
is  supposed  to  occur  on  some  coniferous  host,  and  the  collections 
made  by  us  give  no  clue  to  this  stage  or  its  possible  hosts,  though 
we  have  looked  for  suspicious  Peridermia  on  the  Coni ferae  in 
•that  vicinity. 

GRAPE,  Vitis  sp. 

Downy  Mildew,  Plasmopara  viticola  (B.  &  C.)  Berl.  &  De 
Toni.  This  fungus  is  not  uncommon  on  the  leaves  and  green 
fruit,  but  the  past  year  for  the  first  time  we  have  found  it  here 
on  the  ripening  fruit,  causing  the  brown  rot  described  by  Scrib- 
ner  (Fungous  Diseases  of  the  Grape,  etc.,  p.  48).  In  September 
specimens  of  rotting  white  grapes  were  sent  to  the  station  from 
Hartford  by  Mr.  A.  H.  Newton.  An  examination  showed  that 
this  fungus  was  responsible  for  the  trouble,  though  the  grapes 
were  quickly  infected  by  other  fungi  that  fruited  on  them  and 
so  gave  the  appearance  of  being  the  primary  cause  of  the  rot. 


NOTES   ON    FUNGOUS   DISEASES    FOR    I908.  855 

On  the  young  green  grapes  the  conidial  stage  is  developed  on  the 
exterior,  but  with  the  brown  rot  of  the  ripening  fruit  neither  this 
stage  nor  the  oospores  developed,  though  the  specimens  were 
examined  in  all  stages  of  decay,  for  the  latter,  until  the  end  of 
the  season.  The  characteristic  haustoria  of  the  mycelium,  how- 
ever, easily  distinguishes  the  fungus. 

As  the  mycelium  penetrates  all  through  the  tissue  of  the  grape, 
attempts  were  made  to  secure  artificial  cultures  of  the  fungus, 
as  we  have  done  with  the  downy  mildews  of  the  potato  and  Lima 
bean,  by  placing  infected  tissue  in  nutrient  agar  medium  in  steri- 
lized test  tubes.  In  this  case  we  did  not  succeed,  for  all  the 
grapes  apparently  were  contaminated  with  other  fungi  that 
prevented  the  development  of  the  mildew,  or  else  crowded  it  out. 

The  past  )7ear  a  careful  search  of  grape  leaves  from  different 
sources  late  in  the  fall  disclosed  the  presence  of  the  oospores 
occasionally  in  these.  Farlow  years  ago  reported  finding  these 
spores,  but  they  are  rarely  found  except  when  a  very  careful 
search  is  made  for  them.  There  is  no  external  indication  on  the 
leaf  of  their  presence,  and  the  only  way  to  find  them  is  to  boil 
small  fragments  of  the  suspected  leaves  in  potash,  crushing  the 
tissues  so  that  they  can  be  examined  under  the  microscope,  and 
then  search  until  the  oospores  are  discovered.  We  were  most 
successful  in  finding  them  in  the  tissue  next  the  larger  veins,  but 
did  not  find  them  on  the  twigs,  though  they  have  been  reported 
on  these  in  France. 

Powdery  Mildew,  Uncinula  necator  (Schw.)  Burr.  Plate 
LXII  c.  During  September  an  unusual  appearance  of  this 
commoji  fungus  of  the  grape  was  found  (in  a  single  variety  only, 
on  the  station  grounds)  where  it  produced  small  circular  dis- 
colorations  on  the  stems  of  this  year's  growth,  as  shown  in  the 
illustration.  These  reddish  spots,  about  one-quarter  inch  in 
diameter,  appeared  to  be  made  up  of  much  smaller,  closely  placed 
dots.  The  fungus  in  its  conidial  stage  occurred  inconspicuously 
on  these  and  in  time  disappeared,  so  that  the  cause  of  the  injury 
would  then  have  been  difficult  to  determine.  The  mycelium  of 
this  fungus  ordinarily  develops  externally  on  the  host,  sending 
only  short  branches,  haustoria,  into  the  tissues  for  nourishment, 
but  in  this  case  there  is  a  possibility  that  the  mycelium  secured 
a  firmer  foothold  in  the  plant,  which  might  enable  it  to  live  over 
the  winter  there. 


856         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

PEACH,  Prunus  Per  ska. 

Bacterial  Spot,  Pseudomonas  Pruni  Sm.  Plate  LXIX  a. 
In  the  Station  Report  for  1903,  p.  337,  the  writer  noted  an 
unnamed  bacterial  disease  of  peach  leaves  from  Pomfret,  Con- 
necticut, this  apparently  being  the  first  mention  of  the  disease  in 
literature.  In  the  Report  for  1905,  p.  273,  a  bacterial  spot  of 
plums,  causing  a  purple-black  spotting  of  the  fruit,  was  described 
from  specimens  sent  from  Bridgeport.  This  was  determined  to 
be  the  bacterial  disease  of  plum  named  by  Erwin  F.  Smith 
Pseudomonas  Pruni  (now  called  Bacterium  Pruni  by  Smith), 
and  it  was  suggested  by  the  writer  that  these  two  bacterial 
diseases  might  be  caused  by  the  same  organism.  Recently  Rorer 
(Mycologia  i :  23-7.  1909)  has  practically  demonstrated  the 
identity  of  the  two  diseases,  Rorer  found  the  peach  trouble 
quite  common  in  Arkansas,  where  it  occurred  on  the  twigs  and 
fruit  as  well  as  on  the  leaves.  In  this  state,  on  the  peach,  we 
have  found  the  disease  only  on  the  leaves,  where  it  causes  small 
reddish-brown  spots  which  often  fall  out,  producing  shot  holes, 
and  when  abundant,  the  premature  yellowing  and  fall  of  the 
leaves.  This  year  it  was  more  abundant  and  injurious  than  we 
have  seen  it  before.  We  also  received  for  the  first  time  speci- 
mens of  diseased  plum  twigs  from  Sound  View  that  possibly^ 
were  caused  by  this  organism. 

Collar  Girdle  and  Root  Injury.  Plate  LXVIII  b-c.  In  a  pre- 
vious Report  (1904,  p.  323)  we  briefly  mentioned  winter  injury 
of  the  roots  of  peach  trees  (Mr.  Warner's  of  North  Haven) 
caused  by  the  severe  winter  of  1903-04.  The  winter  of  1907-08 
apparently  caused  more  of  this  trouble — aggravated  in  part 
possibly  by  a  weak  condition  of  the  trees  due  to  the  1907 
drought — than  has  yet  been  reported  in  the  peach  orchards  of 
this  state.  The  trouble  was  first  called  to  the  attention  of  the 
station  by  Mr.  J.  H.  Hale,  who  asked  for  an  investigation  of 
the  trouble.  Mr.  Hale  wrote:  "There  has  been  a  tremendous 
dying  of  peach  trees  around  these  parts  the  past  two  or  three 
weeks,  after  they  began  to  leaf  out.  Yesterday  morning  Albert 
Carini,  who  lives  in  the  eastern  part  of  South  Glastonbury,  came 
to  me  with  a  tale  of  practically  six  hundred  dead  and  dying  trees 
in  an  orchard  that  looked  all  right  four  or  five  days  before." 
Other  growers  in  the  state  lost  occasional  trees,  but  in  few 
orchards  was  the  injury  so  severe  as  in  Mr.  Carini's. 


NOTES    ON    FUNGOUS   DISEASES    FOR    I908.  857 

In  the  absence  of  the  writer  Dr.  Britton  investigated  this 
trouble,  and  we  are  indebted  to  him  for  the  photographs  and 
notes  used  here.  The  examination  showed  that  the  diseased  trees 
had  started  to  develop  their  foliage,  but  this  soon  turned  yellow 
and  dropped  off  before  maturing.  Some  of  the  trees  by  June  2d 
had  dropped  all  of  their  foliage  except  small  tufts  at  the  end 
of  the  twigs,  but  the  fruit  still  adhered.  The  trouble  was  found 
to  be  due  to  winter  injury,  which  killed  the  roots  and  girdled  the 
bark  at  the  base  of  the  tree,  reaching  above  the  ground  two  or 
three  inches  and  forming  the  so-called  "collar  girdle."  This  bark 
could  easily  be  peeled  off,  as  shown  in  the  illustration,  Plate 
LXVIII  b,  and  the  demarcation  between  the  injured  and  living 
bark  was  pronounced.  Some  indication  of  injury  to  the  wood  at 
the  girdle  was  also  shown  by  its  brownish  color.  Some  of  the 
trees  were  dead  only  on  one  side,  and  in  that  case  the  roots  were 
not  all  killed  or  the  bark  completely  girdled ;  see  Plate  LXVIII  c. 
The  trouble  at  Mr.  Carini's  was  chiefly  on  one  variety,  apparently 
a  tender  one,  which  had  been  bought  for  Elberta,  but  did  not 
prove  true  to  name. 

This  injury  to  peach  trees  is  most  likely  to  occur  on  places 
where  the  soil  is  not  properly  drained,  or  where  the  trees  are 
exposed  so  that  the  snow  is  blown  off  from  the  ground  around 
the  trees.  The  snow  acts  as  a  mulch,  and  is  of  great  value  in 
protecting  the  roots  and  base  of  the  tree.  Cover  crops  or  a 
vegetable  mulch  is  of  similar  service  where  injury  of  this  kind 
is  likely  to  occur.  Likewise,  growers  in  this  state  have  found 
it  profitable,  especially  with  young  trees,  to  throw  up  the  dirt 
around  the  base  in  the  fall  and  then  scrape  it  away  again  in 
spring. 

TOMATO,  Lycopersicum  esculentum. 

Chlorosis  (Infectious).  Plate  LXVI  b.  In  the  last  Report 
(1907,  p.  362)  we  mentioned  a  chlorosis  trouble  of  tomatoes  seen 
in  the  field  and  supposed  to  be  due  to  the  effects  of  frost,  the 
plants  having  been  injured  by  it  in  the  spring.  Whether  or  not 
this  was  the  cause  we  cannot  say  positively,  but  attempts  to 
produce  this  trouble  in  young  greenhouse  plants  by  exposing 
them  to  the  cold  so  that  they  were  more  or  less  seriously  injured 
were  not  successful.  The  past  season  we  saw  this  trouble  again 
in  two  or  three  different  fields,  and  by  using  juice  from  these 


858         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

plants  in  one  case  were  able  to  produce  the  same  disease  on 
healthy  tomatoes,  and  also  on  tobacco.  This  shows  that  this 
tomato  chlorosis  is  infectious  and  of  the  same  nature  as  the  calico 
of  tobacco.  In  greenhouse  experiments  we  have  frequently  pro- 
duced chlorosis  in  tomatoes  from  juice  from  calicoed  tobacco  and 
then  carried  it  back  to  the  tobacco  again  from  the  tomato.  In 
one  of  these  experiments  (see  illustration)  the  effect  on  the 
tomato  was  to  produce  little  visible  calico,  but  rather  a  severe 
bacterial-like  disease  of  the  tomatoes.  This  possibly  (though  we 
hardly  think  so)  was  of  the  nature  of  a  burn,  since  it  was  worse 
in  plants  sprinkled  with  water  after  handling  them  with  the 
calicoed  juice  on  the  hands  to  produce  the  infection.  However, 
we  have  at  other  times  seen  these  small  bacterial-like  spots  both 
on  calicoed  and  healthy  tomatoes. 

C.      DISEASES    NOT   PREVIOUSLY   REPORTED. 

ASPARAGTJS,  Asparagus  officinalis. 

Smoke  (Gas)  Injury.  Early  in  October  the  writer  was  called 
to  examine  a  field  of  asparagus  claimed  by  the  owner  to  have 
been  seriously  injured  some  time  before  (late  August  or  Sep- 
tember) by  the  smoke  from  an  adjacent  brick  kiln.  It  seems  that 
in  muggy  weather,  when  the  wind  was  right,  the  smoke  was 
sometimes  swept  down  across  the  field  for  a  time,  and  the  tops 
were  killed  or  severely  injured.  In  the  previous  year  such  injury 
had  resulted  and  the  owner  of  the  brick  kiln  had  paid  damages 
for  the  same.  This  year  the  owner  of  the  kiln  claimed  that 
before  the  smoke  was  blown  over  the  field  the  plants  were  as 
nearly  dead  as  when  seen  later  by  the  writer.  Refusing  to  pay 
damages,  he  was  sued. 

After  a  careful  examination,  the  writer  came  to  the  conclusion 
that  while  there  was  some  slight  indication  of  gas  injury  to  the 
field  (as  shown  by  a  streak  through  the  center  with  more  com- 
pletely dead  tops  in  an  adjacent  field),  the  main  injury  had  not 
been  caused  by  the  smoke  of  this  year.  The  asparagus  tops  in 
fields  in  the  near  vicinity  and  elsewhere  were  in  no  better  shape 
than  those  here  at  this  time,  due  to  the  severe  droughts  of  the 
year.  The  asparagus  in  this  field  had  been  very  severely  ridged, 
even  for  a  wet  season,  and  so  must  have  suffered  during  the 
present  dry  one,  which  no  doubt  was  largely  responsible  for  the 


NOTES    ON    FUNGOUS   DISEASES    FOR    IQOS.  859 

dead  roots  rather  than  the  gas.  As  the  tops  had  been  injured 
the  year  before  by  the  gas,  this  no  doubt  weakened  the  plants  and 
made  them  more  susceptible  to  injury  by  the  drought.  This 
previous  injury,  however,  had  been  settled  for.  It  is  generally 
understood  that  it  is  the  sulphurous  gas  in  the  smoke  that  causes 
injury  to  vegetation  under  such  conditions. 

AZALEA,  Azalea  sps. 

Powdery  Mildew,  Microsphaera  Alni  (Wallr.)  Wint.  The 
mildew  on  this  host  seemed  to  confine  itself  to  the  under  surface 
of  the  leaves,  forming  there  a  more  or  less  conspicuous  white 
coating,  with  the  perithecia  scattered.     See  also  New  Jersey  Tea. 

BALM,  BEE,  Monarda  didyma. 

Rust,  Puccinia  Menthce  Pers.  This  forms  the  II  and  III 
stages,  frequently  together,  as  light  and  dark,  very  small,  dusty 
pustules,  chiefly  on  the  under  side  of  the  leaves,  causing  more  or 
less  spotting  of  the  upper  surface.  It  was  found  in  a  local 
nursery  in  September  (rather  abundant),  on  cultivated  specimens 
of  the  above  host  and  its  variety  alha.  It  is  not  an  uncommon 
rust  on  some  of  the  wild  mints,  especially  the  peppermint,  Mentha 
piperita. 

BEAK'S,  Phaseolus  sps. 
Chlorosis  {Infections?).  Plate  LXI  a.  In  the  last  Report  of 
the  station,  1907,  p.  343,  a  chlorosis  trouble  of  the  Lima  bean 
was  described  which  did  not  seem  to  be  infectious.  (Plate 
LXI  b  of  present  report.)  During  September  of  the  past  year 
certain  of  the  plants  of  both  Lima  and  string  beans  on  a  market 
garden  farm  in  Westville  showed  a  chlorosis  somewhat  different 
from  that  noticed  the  year  before,  and  which  in  general  appear- 
ance resembled  very  closely  the  chlorosis  (mosaic,  or  calico) 
troubles  of  tobacco,  tomatoes  and  muskmelons  (g.  ■z^.).  The  illus- 
tration gives  a  general  idea  of  this  trouble,  the  tissues  around  the 
veins  showing  usually  the  normal  green,  and  those  between  a 
lighter  green  color,  thus  giving  a  mottled  or  mosaic  effect.  With 
the  non-infectious  chlorosis  of  the  Lima  bean  mentioned  above, 
the  lighter  green  had  more  of  yellowish  cast,  quite  similar  to 
insect  or  drought  injury.    Preliminary  experiments  in  the  green- 


S6o        CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

house,  using  dried  specimens  of  both  Lima  and  string  bean  leaves 
three  months  old,  soaked  in  water  for  a  short  time  which  was  then 
applied  to  young  Lima  and  string  beans,  were  not  successful  in 
producing  this  disease,  at  least  not  very  evidently.  Neither  did 
tobacco  water  from  dried  calicoed  tobacco  leaves  produce  it, 
though  such  water  will  easily  produce  calico  in  young  tobacco 
plants.  However,  these  experiments  were  not  extended  enough 
to  say  definitely  that  the  disease  is  not  infectious.  Experiments 
with  the  fresh  juice  will  be  tried  later,  if  possible,  as  we  are 
strongly  of  the  opinion  that  this  is  an  infectious  chlorosis. 

BEETS,  Beta  vulgaris. 

Drop  Dampening-off,  Sclerotinia  Libertiana  Fckl.  The 
same  fungus  which  caused  the  drop  trouble  of  parsnips  and 
lettuce  (q.  v.)  at  Farnham's,  also  caused  a  serious  dampening 
off  of  seedling  beets  (also  somewhat,  apparently,  of  lettuce, 
cabbage  and  radishes)  in  the  hotbeds  about  the  middle  of  March, 
1909.  So  many  of  the  seedling  beets  were  dampened  off  that 
some  of  the  frames  had  to  be  replanted,  and  in  these  the  seedlings 
again  dampened  off,  but  not  nearly  so  badly  as  at  first.  This 
indicates  that  the  extra  warm  condition  of  the  hotbeds  soon  after 
making  was  an  important  factor  in  the  trouble.  Also  with  the 
later  planting  the  beds  could  be  aired,  when  necessary,  with  less 
danger.  Unlike  the  greenhouse  conditions,  where  this  fungus 
damaged  the  parsley  and  lettuce,  there  was  seen  little  growth  of 
the  mycelium  exposed  on  the  soil,  probably  because  there  was 
little  dying  vegetation  there  for  its  development. 

About  the  time  of  the  second  planting,  a  portion  of  the  bed, 
under  two  frames  at  the  end,  was  treated  with  formalin  (at  the 
rate  of  one  part  formalin  to  eighty  parts  of  water,  and  used  at 
the  rate  of  two-thirds  gallon  per  square  foot  of  bed).  The  bed 
was  left  for  five  days  to  allow  the  fumes  to  escape,  and  seeded 
again  with  beets.  In  this  treated  soil  by  far  the  best  stand  any- 
where on  the  beds  was  obtained  and  practically  no  dampening  off 
occurred.  The  only  check  in  this  experiment  was  the  adjacent 
frames,  reseeded  eleven  days  before,  where  the  dampening  off 
had  made  the  rows  quite  irregular.  One  objection  to  treatment 
in  this  way  is  that  the  beds  after  being  made  must  lie  vacant  a 
week  before  seeding  in  order  to  allow  the  fumes  to  escape. 
Whether  or  not  the  compost  used  over  the  manure  could  be 


NOTES    ON    FUNGOUS   DISEASES    FOR    I908.  861 

treated  some  time  before  placing  it  in  the  beds,  and  the  same 
results  be  obtained,  can  only  be  determined  by  experimentation. 
If  so,  then  the  beds  could  be  seeded  as  soon  after  making  as 
the  temperature  allowed. 

CHKYSANTHEMTJM  (POMPON),  Chrysanthemum  indicum. 

Rust,  Puccinia  Chrysanthemi  Roze.  We  found  this  rust  not 
uncommon  on  pompons,  especially  a  variety  called  Sunset,  last 
October,  on  outdoor  plants  in  a  local  nursery;  the  rust,  as  on 
greenhouse  chrysanthemums,  formed  only  its  uredinial  stage. 
These  uredinial  sori,  which  occur  on  the  under  surface  of  the 
leaves,  were,  however,  somewhat  smaller  than  those  on  green- 
house varieties,  but  the  spores  did  not  appear  to  be  different. 
The  rust  often  kills  the  tissue  so  that  variable-sized,  reddish- 
brown  spots  show  on  both  surfaces  of  the  leaves. 

DAHLIA,  Dahlia  variabilis. 

Dry  Weather  Injury.  During  the  past  summer  there  were  a 
number  of  complaints  of  injury  to  dahHas  from  some  cause. 
In  the  vicinity  of  New  Haven  the  writer  observed  that  they  did 
poorly,  and  the  trouble  apparently  was  noticed  in  other  states 
than  this.  The  trouble  was  something  like  the  yellows  of  asters. 
The  plants  were  more  or  less  undersized,  and  the  foliage  (less 
luxuriant,  somewhat  misshapen,  and  turning  yellowish  at  the 
margins)  frequently  slowly  died.  The  plants  also  flowered  much 
less  than  usual,  and  the  flowers  were  of  smaller  size  and  often 
one-sided. 

A  careful  examination  of  diseased  plants  sent  by  Mr.  H.  M. 
Robinson  of  Danbury,  who  complained  that  while  the  trouble 
showed  somewhat  in  1907,  it  was  much  worse  in  1908,  revealed 
no  sign  of  any  insect  or  fungus  as  the  cause  of  the  trouble. 
Cross  sections  of  the  stem  under  the  microscope  showed  certain 
cells  of  the  bark  with  discolored  walls  and  contents  shrunken; 
not  infrequently  lines  of  these  injured  cells  extended  out  from 
the  fibro-vascular  bundles  toward  the  surface  of  the  stem.  No 
signs  of  fungous  threads  were  found  as  a  cause  of  these  diseased 
and  dead  cells.  Everything  taken  into  account,  there  seems  to 
be  no  doubt  that  the  trouble  was  a  physiological  one,  due  to  the 
dry  weather  of  the  early  part  of  the  season,  mention  of  which  has 


862         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-1908. 

already  been  made.  Many  of  the  ornamental  plants  suffered 
from  this  drought,  but  more  or  less  recovered  during  the  later, 
more  moist  weather.  The  injury  to  the  dahlias,  however,  was 
sufficient  to  severely  affect  them,  especially  at  the  flowering 
period.  Perhaps  the  injury  may  have  been  slightly  accentuated 
by  injury  to  the  tubers  from  the  drought  of  the  previous  season, 
in  which  case  the  plants  the  coming  season  may  show  the  effect 
somewhat,  even  if  it  proves  a  favorable  season. 

DANDELIOIT,  Taraxacum  officinale. 

Leaf  Spot,  Ramularia  Taraxaci  Karst.  This  forms  roundish 
spots,  at  first  purplish  but  finally  brownish,  on  the  leaves,  having 
fine  concentric  rings  and  often  a  purplish  border.  They  vary 
in  size  from  a  pin  head  to  nearly  half  an  inch.  While  not  uncom- 
mon on  the  wild  dandelion,  it  does  comparatively  little  harm  to 
the  cultivated  plants,  probably  because  these  are  renewed  each 
year  from  the  seed  rather  than  grown  continuously  from  the 
roots.  There  seems  to  be  little  or  no  reason  for  considering 
Peck's  species,  Ramularia  lineola,  distinct  from  this. 

GOURD,  BOTTLE,  Lagenaria  vulgaris. 

Downy  Mildew,  Peronoplasmopora  cubensis  (B.  &  C.)  Clint. 
This  mildew  was  seen  for  the  first  time  last  summer,  in  a  West- 
ville  garden,  on  this  host.  It  was  likewise  on  the  common  gourd, 
Cucurbita  Pepo.  In  both  cases  the  fungus  produced  on  the 
leaves  numerous  conspicuous  reddish-brown  spots  about  one- 
quarter  of  an  inch  in  diameter,  which  soon  ran  together.  The 
fungus  showed  somewhat  as  a  faint  growth  on  the  under  surface. 
Although  a  careful  search  was  made  on  these  hosts,  as  well  as  on 
the  numerous  varieties  of  muskmelons  in  our  experimental  tests, 
throughout  the  entire  season,  we  were  still  unable  to  discover 
the  oospores,  or  winter  stage,  of  this  fungus. 

LAEKSPTJR,  Delphinium  sp. 

Bacterial  Spot,  Bacillus  Delphini  Sm.  Plate  LXIVc. 
While  we  have  seen  this  disease  before,  we  have  paid  no  especial 
attention  to  it,  thinking  it  probably  due  to  injury  by  sucking 
insects.  The  past  summer  cultivated  specimens  of  larkspur  on 
the  Experiment  Station  grounds  showed  the  trouble  quite  promi- 


NOTES    ON    FUNGOUS   DISEASES    FOR    I908.  863 

nently.  It  is  chiefly  a  leaf  injury,  developing  as  purple-black, 
irregular  spots  (evident  on  both  surfaces)  which  vary  from  those 
scarcely  discernible  up  to  a  quarter  of  an  inch  in  diameter,  and 
where  thickly  placed,  become  more  or  less  merged.  An  exami- 
Eiation  of  the  diseased  tissue  under  the  microscope  showed  the 
presence  of  plenty  of  bacteria.  No  cultures  or  inoculations  were 
made,  however.  So  far  as  the  writer  is  aware,  the  only  mention 
of  a  bacterial  disease  of  this  host  is  in  a  short  note  by  Erwin  F. 
Smith  (Science  19:  417.  1904),  which  is  an  abstract  of  a  paper 
given  before  the  A.  A.  A.  S.  A  brief  account  of  this  disease  and 
the  organism  causing  it  (which  is  named  as  a  new  species),  is 
given  there.  Smith  produced  the  disease  on  various  varieties  of 
Delphinium  from  pure  cultures.  In  his  Bacteria  in  Relation  to 
Plant  Disease,  1905,  Smith  also  gives  a  photograph  of  diseased 
leaves. 

•  LETTUCE,  Lactuca  sativa. 

Drop,  Sclerotinia  Libertiana  Fckl.  Plate  LXIII.  While  this 
fungus  has  been  known  for  some  time  as  a  serious  enemy  of 
greenhouse  lettuce,  especially  in  the  great  Boston  lettuce  district 
(see  Bull.  69,  Mass.  Agr.  Exp.  Station,  by  Stone  and  Smith), 
and  no  doubt  has  occasionally  done  injury  to  some  extent  in  this 
state,  we  have  not  previously  come  across  it.  In  Mr.  Farnham's 
greenhouse,  where  parsley  {q.  v.)  was  injured  by  this  fungus, 
that  crop  was  followed  by  lettuce  without  changing  the  soil. 
While  some  damage  resulted  to  the  lettuce,  the  injury  on  the 
whole  was  not  so  great  as  one  might  expect,  knowing  that  some- 
times as  high  as  ninety  per  cent,  of  the  lettuce  heads  have  been 
killed  by  this  fungus  in  Massachusetts.  However,  before  setting 
out  the  lettuce,  all  the  refuse  containing  the  fungus  was  removed 
from  the  soil;  the  lettuce  was  frequently  cultivated  to  keep  the 
fungus  from  developing  on  the  surface  of  the  soil,  and  greater 
care  was  taken  with  watering,  especially  during  cloudy  weather. 
Out  of  the  whole,  only  about  five  per  cent,  of  the  lettuce  heads 
were  finally  carried  off  by  the  drop. 

A  portion  of  the  soil  in  this  greenhouse  shortly  before  the 
lettuce  was  set  out  was  treated  with  formalin,  rate  of  one  part  of 
formalin  to  one  hundred  of  water.  This  was  sprinkled  over  the 
soil  gradually  until  there  was  used  about  three-fourths  of  a 
gallon  per  square  foot.  The  ground  was  covered  with  canvas 
61 


864         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

for  a  day  and  then  aired  for  a  week  before  setting  the 
lettuce.  This,  however,  did  not  prove  long  enough  for  the  fumes 
to  get  out  of  the  soil,  although  it  was  also  lightly  spaded  three 
days  before  use,  and  as  a  result  the  lettuce  began  to  wilt  the 
next  day,  and  in  less  than  a  week  was  all  dead.  We  have  used 
the  soil  in  greenhouse  benches  inside  of  eight  days  after  treat- 
ment, but  as  this  bed  was  on  the  ground  itself,  it  did  not  dry  out 
so  easily.  So  it  is  not  wise  to  use  the  treated  soil  under  ten 
days  where  plants  are  set  out,  or  for  a  week  where  it  is  seeded. 
The  second  set  of  plants,  put  out  a  few  days  after  the  first  were 
removed,  started  off  very  nicely,  and  eventually  formed  the  finest 
looking  lot  of  heads  in  the  greenhouse.  They  had  a  finer  green 
color,  grew  somewhat  faster  and  more  uniformly,  and  not  a 
single  one  was  lost. 

Possibly  where  the  sclerotia  are  present  abundantly  in  the  soil, 
the  formalin  treatment  would  not  be  so  effective.  Stone  and 
Smith  found  that  the  use  of  hot  water,  heating  the  soil  up  to  176° 
to  186°,  was  very  beneficial  in  destroying  the  fungus  and  pre- 
venting subsequent  trouble  from  the  drop.  Steam  has  also  been 
used  for  the  same  purpose. 

The  trouble  is  called  the  drop  because  the  fungus  attacks  the 
base  of  the  leaves,  rotting  them  there  and  causing  them  to  fall 
over.  This  is  shown  very  nicely  by  Plate  LXIII  c,  which  pic- 
tures a  check  and  an  inoculated  plant.  The  inoculated  plant  had 
a  small  amount  of  the  fungus  from  a  pure  culture  placed  on  the 
base  of  the  leaves  that  show  the  drop  just  two  days  before  the 
photograph  was  taken;  at  the  end  of  four  days  all  of  the  leaves 
had  fallen  over,  and  by  the  end  of  the  week  the  plant  was  entirely 
dead. 

LILY,  COMMON  WHITE,  Lilium  candidum. 

Bacterial  Spot  ?  Plate  LXIV  b.  This  disease  was  found  on 
cultivated  lilies  during  October  in  a  local  nursery.  The  oval 
spots  are  quite  conspicuous,  the  largest  varying  from  one-half 
inch  to  one  inch  in  length.  The  greater  portion  of  the  spot  is 
occupied  by  a  semi-transparent  portion  in  which  the  chlorophyll 
often  entirely  disappears,  and  surrounding  this  is  a  smaller 
purplish  border.  In  dried  specimens  one  can  read  print  through 
the  transparent  portion  if  the  leaf  is  placed  on  the  page.  The 
spots    contain   numerous    bacteria,    but    also    occasionally    some 


NOTES    ON    FUNGOUS   DISEASES    FOR    I908.  865 

mycelial  threads  of  a  fungus,  though  there  was  no  sign  of  this 
fruiting  on  the  exterior.  As  yet  cultures  and  inoculations  have 
not  been  made,  so  that  it  is  not  positively  known  that  the  disease 
is  of  bacterial  origin,  though  from  general  appearances  there 
seems  to  be  little  reason  to  disbelieve  that  it  is  such.  So  far,  the 
writer  has  found  in  literature  no  mention  of  a  similar  trouble  of 
lilies  due  to  bacteria. 

MTISKMELON,  Cucumis  melo. 

Chlorosis  {Infectious?).  Plate  LXI  c.  This  physiological 
trouble  was  first  seen  the  past  summer  on  certain  varieties  of  the 
muskmelons  grown  for  the  station  by  Mr.  Frisbie  of  Southington. 
It  appeared  first  and  most  prominently  on  the  Extra  Early  Grand 
Rapids.  In  general,  the  appearance  of  the  disease  is  very  similar 
to  the  calico  disease  of  tobacco,  as  the  leaves  are  irregularly 
mottled  with  lighter  and  darker  green  areas,  the  darker  green 
patches  surrounding  the  larger  veins,  as  shown  in  the  illustration. 
The  trouble  is  not  severe  enough  to  kill  the  tissue  of  the  leaves, 
and  therefore  does  not  very  seriously  interfere  with  their  normal 
functions.  Mr.  Frisbie  said  that  he  had  observed  this  trouble 
before  on  muskmelons.  So  far  as  the  writer  is  aware,  it  is  not 
recorded  in  the  literature  of  plant  diseases  on  this  host,  though 
Selby  of  Ohio  has  briefly  described  the  same  or  a  very  similar 
trouble  on  cucumbers  (Ann.  Rept.  Ohio  St.  Hort.  Soc.  1902:  109. 
1903.  Ihid.  1903:  128.  1904).  In  Bull.  Ohio  Agr.  Exp. 
Station  156,  p.  90,  he  says :  "It  seems  now  that  we  must  class  the 
mosaic  disease  of  tobacco,  the  yellows  of  the  peach,  peach  rosette, 
the  mosaic  disease  of  tomatoes,  and  the  mosaic  disease  of  forcing 
house  cucumbers,  which  the  writer  has  recently  investigated  at 
Ashtabula,  Ohio,  in  one  and  the  same  group  of  maladies." 

This  disease  is  very  similar  in  appearance  to  the  calico  of 
tobacco ;  and,  as  the  melons  were  on  land  that  had  recently  been 
in  tobacco,  it  seemed  quite  likely  that  the  disease  was  due  to  the 
same  cause.  In  order  to  determine  if  it  were  infectious,  the 
writer  made  a  preliminary  experiment  in  the  field,  similar  to 
experiments  that  will  produce  the  calico  in  tobacco.  Some  cali- 
coed  muskmelon  leaves  were  crushed  in  the  hands,  and  then  seven 
healthy  plants  of  different  varieties  at  the  end  of  the  rows  were 
handled,  and  bits  of  the  crushed  leaves  left  on  them.  Unfortu- 
nately, the  plants  were  not  examined  until  some  three  or  four 


866         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

weeks  later,  when  all  of  them  showed  more  or  less  of  the 
chlorosis,  but  as  some  of  the  neighboring  untouched  plants  also 
showed  the  trouble  it  was  impossible  to  say  positively  that  the 
disease  was  induced  by  the  touching  in  the  experimental  plants. 
Infection  experiments  will  be  tried  again.  The  same,  or  a  very 
similar  trouble,  was  seen  the  past  year  on  Lima  and  string  beans 
and  tomatoes,  as  well  as  on  tobacco. 

HEW  JEESEY  TEA,  Ceanothus  americamis. 

Powdery  Mildew,  Microsphaera  Alni  (Wallr.)  Wint.  Plate 
LXVI  a.  This  mildew  was  found  on  French  seedHngs  of  the 
above  host  in  a  local  nursery.  There  seemed  to  be  considerable 
difference  as  to  its  abundance  on  the  different  plants.  It  forms 
a  white  coating  on  both  the  upper  and  lower  surface  of  the  leaves, 
but  showing  more  prominently  on  the  upper.  Sometimes  this 
coating  entirely  covers  the  surface  of  the  leaf,  as  if  painted  over 
with  a  white  paint.  In  such  cases  the  perithecia  often  stand  out 
quite  plainly  in  small  circular  dark  colonies  about  a  quarter  of 
an  inch  across,  as  shown  in  the  illustration.  This  same  mildew 
is  common  on  this  host  here  in  its  wild  state.  We  have  reported 
it  before  only  on  the  lilac,  but  in  this  Report  it  is  listed  also  on 
the  azalea  and  the  Pagoda  tree,  q.  v.  Its  appearance  on  these 
different  hosts  varies  somewhat. 

OAK,  Quercus  sp. 

Limb  Gall  {Bacterialf).  Plate  LXV  a-b.  For  a  long  time 
the  writer  has  observed  galls  on  the  limbs  of  various  trees,  such 
as  the  oak,  hickory  and  maple,  but  has  never  definitely  known  the 
cause  of  these.  They  vary  somewhat  in  size  and  duration  on  the 
different  hosts,  and  may  not,  of  course,  all  have  the  same  causal 
agent,  though  their  general  character  is  the  same.  The  general 
impression  seems  to  be  that  these  are  the  results  of  insect  attack, 
but  Dr.  Britton  states  that  the  entomologists  do  not  recognize 
them  as  such.  The  writer,  in  common  with  some  other  botanists, 
has  believed  that  possibly  they  are  the  result  of  bacterial  action, 
and  since  the  researches  of  Smith  and  Townsend  have  shown 
that  the  galls  of  peach,  etc.,  which  in  appearance  have  consider- 
able in  common  with  these  galls,  are  due  to  bacteria,  this  belief 
has  been  strengthened. 


NOTES   ON    FUNGOUS   DISEASES    FOR    I908.  867 

The  past  winter  the  Hartford  Superintendent  of  Parks,  Mr. 
G.  A.  Parker,  sent  the  writer  specimens  of  the  gall  on  oak,  from 
Keney  Park.  Mr.  Parker  stated  that  the  trouble  was  first 
noticed  several  years  ago  on  a  single  tree,  and  had  since  slowly 
spread  over  the  tree  and  to  two  adjacent  trees.  An  examination 
showed  that  the  galls  varied  in  size  from  that  of  a  pea  up  to  a 
small-sized  pumpkin.  There  was  no  evidence  of  insect  work  on 
them,  though  other  small  galls  on  the  twigs  were  of  that  nature. 
The  galls  in  cross  section  (see  illustration)  showed  that  the 
swelling  was  due  to  an  unusual  enlargement  of  the  wood  (and 
to  a  less  degree,  of  the  bark),  and  exhibited  a  semi-radiating 
structure  from  a  common  center,  with  black  spots  showing  fre- 
quently in  the  otherwise  normally  colored  wood.  The  large  galls 
were  apparently  some  years  old,  and  had  increased  in  size  each 
year.  Some  idea  of  their  age  could  be  obtained  by  cross  sections, 
though  the  annual  rings  of  growth  were  not  very  distinct.  In 
the  largest  knots,  not  more  than  ten  or  twelve  of  these  rings 
could  be  made  out,  but  usually  after  four  or  five  years  the  galls 
seem  to  stop  growth  and  begin  their  gradual  decay.  The  largest 
knots  had  ceased  to  grow;  the  bark  and  wood  were  both  dead, 
and  the  former  was  more  or  less  decayed  also.  On  the  whole, 
the  oak  galls  attain  a  larger  size  and  are  more  lasting  than  the 
hickory  galls,  whicli  seem  to  be  largely  annual,  and  perpetuate  the 
trouble  by  new  galls  at  the  margin  of  the  old  ones.  The  surface 
of  the  galls  shows  a  corrugated  and  rougher  character  than  the 
bark  of  the  limbs  on  which  they  occur.  Unlike  the  crown  gall, 
these  galls  occur  on  the  limbs  high  up  in  the  tree. 

The  writer,  early  in  March,  made  a  number  of  inoculations  in 
Lima  bean  agar  with  tissue  from  the  interior  of  these  galls,  but 
obtained  no  growths.  Perhaps  such  growths  were  prevented  by 
the  tannin-like  substance  that  diffused  from  the  tissues  and  dis- 
colored the  medium  for  some  distance  around.  Possibly  cultures 
from  new  galls  in  the  spring  might  give  different  results. 

OKEA,  Hibiscus  esculent  us. 

Powdery  Mildew,  Erysiphe  cichoraceartim  DC.  This  fun- 
gus forms  a  greyish-white,  mealy,  and  rather  inconspicuous 
growth,  in  spots,  or  eventually  covering  the  whole  surface,  on 
the  upper  sides  of  the  leaves,  rarely  forming  a  very  slight  growth 


868        CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

on  the  under  surface.  Only  the  conidial  stage  was  found,  as  is 
always  the  case  on  the  squash,  pumpkin,  etc.,  and  as  this  stage 
cannot  be  distinguished  from  that  on  those  hosts,  I  have  placed 
it  under  the  same  species.  Apparently  the  powdery  mildews  do 
not  occur  commonly  on  the  Malvaceae,  as  Farlow  lists  only  one 
host  in  his  Host  Index,  and  Salmon,  in  his  monograph,  apparently 
only  two.  Neither  gives  this  host.  deThiimen,  however,  judg- 
ing from  his  description  (Grev.  6:  102)  described  this  fungus 
under  the  name  Oidium  Ahelmoschi,  having  received  it  on  this 
host  from  Egypt. 

PAGODA  TREE,  Sophora  japonica. 

Powdery  Mildew,  Microsphaera  Alni  (Wallr.)  Wint.  This 
host  is  a  small  tree  that  comes  from  China  and  Japan  and  is 
occasionally  grown  for  ornament  here.  The  mildew,  apparently, 
has  not  been  reported  on  it  before,  at  least  this  host  is  not  in 
the  host  indexes  of  Farlow,  Saccardo  or  Salmon,  or  in  the'latter's 
Hosts  of  Japanese  Mildews.  It  was  found  not  uncommon  in  a 
local  nursery,  where,  in  September,  it  formed  a  grayish-white 
mealy  growth,  chiefly  on  the  upper  sides  of  the  leaves,  usually 
covering  the  entire  surface  of  the  leaflets.  Very  few  perithecia 
were  formed.     See  also  New  Jersey  Tea. 

PARSLEY,  Petroselinum  sativum. 

Drop,  Sclerotinia  Libertiana  Fckl.  Plate  LXIII.  In  Febru- 
ary, 1909,  Mr.  A.  N.  Farnham,  the  market  gardener  of  West- 
ville,  called  my  attention  to  an  unusual  trouble  he  was  having 
with  parsley  in  his  greenhouse.  The  parsley  was  grown  on  the 
ground  in  rows,  much  after  the  manner  of  its  cultivation  in  the 
field.  As  the  soil  is  changed  each  year,  hitherto  no  trouble  had 
been  had  with  soil  fungi,  but  this  year  the  soil  had  become 
infected  in  some  m^anner,  perhaps  from  the  manure  used,  and 
this,  with  difficulty  in  properly  regulating  the  watering  at  the 
time  the  plants  were  well  covering  the  ground,  started  the  drop 
fungus  to  work  in  good  shape.  This  fungus  develops  its  sterile 
mycelium  as  a  white  growth  on  the  surface  of  the  ground, 
especially  on  the  decaying  vegetation,  and  also  works  into  the 
living  stems  and  leaves,  rotting  them  off.  Occasionally  it  forms 
small,    black,    tuber-like    bodies,    called    sclerotia    (see    artificial 


NOTES    ON    FUNGOUS   DISEASES    FOR    I908.  869 

culture  shown  in  Plate  LXIIIb),  slightly  embedded  in  these 
rotted  stems.  Where  the  soil  is  used  year  after  year  this  trouble 
is  likely  to  become  increasingly  serious,  as  these  sclerotial  bodies 
carry  the  fungus  over  from  year  to  year,  even  if  the  soil  thor- 
oughly dries  out  in  the  summer  time.  While  the  fungus  in  this 
case  injured  the  plants  so  severely  as  to  make  an  uneven  growth, 
killing  them  out  entirely  in  spots,  after  the  first  cutting,  by 
gathering  up  all  the  refuse  containing  the  fungus,  and  by 
cultivating  the  ground  frequently  and  using  extra  care  in  water- 
ing, the  trouble  was  kept  down  so  that  the  injury  was  consider- 
ably lessened  in  the  second  cutting.  This  same  fungus  is  often 
quite  injurious  to  greenhouse  lettuce.  A  fuller  description  is 
given  here  under  that  host,  as  part  of  the  house  was  afterwards 
planted  to  that  crop. 

PEACH,  Prunus  Persica. 

Gummosis.  Plate  LXVIII  a.  The  branches  shown  in  the 
illustration  were  from  a  small  orchard  in  Centerville  in  which  a 
number  of  the  trees  developed  this  trouble.  An  examination  of 
the  orchard  showed  that  the  wood  of  most  of  these  trees  had  been 
more  or  less  severely  winter  injured  a  few  years  previously,  and 
had  not  been  pruned  since  to  start  new  growth.  Apparently  the 
gummosis  trouble  was  a  secondary  result  of  this  winter  injury, 
due  possibly  to  bacteria  or  fungi  that  gained  entrance  to  the 
branches  because  of  their  weak  condition  and  produced  diseased 
places  in  the  bark,  which  cracked  open  and  formed  a  deposit  of 
gum  around  the  wound.  Gummosis  has  been  attributed  to  a 
variety  of  causes,  but  we  doubt  if  any  particular  organism,  in  the 
present  case,  was  wholly  responsible  for  the  trouble. 

Little  Peach.  At  the "  annual  meeting  of  the  Connecticut 
Pomological  Society  at  Hartford  in  February,  1908,  Mr.  C.  E. 
Lyman  of  Middlefield  called  attention  to  a  trouble  in  his  peach 
orchard  which  he  took  to  be  little  peach.  The  past  season  this 
trouble  has  been  definitely  identified  by  Mr.  M.  B.  Waite,  of  the 
United  States  Department  of  Agriculture,  and  has  been  noticed 
in  other  orchards,  apparently  more  abundant  than  hitherto.  As 
this  trouble  is  said  to  be  quite  serious  in  Michigan,  its  appearance 
in  this  state  is  worthy  of  careful  attention.  Little  peach  was  first 
investigated  in  Michigan,  by  Erwin  F.   Smith,  who   found  the 


870        CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

fibrous  rootlets  of  the  diseased  trees  more  or  less  dried  up.  Mr. 
Waite  holds  that  it  is  a  trouble  quite  similar  to  the  yellows  and 
that  it  is  contagious,  so  that  infected  trees  should  be  promptly 
dug  up  and  destroyed.  By  this  means  the  trouble  is  said  to  be 
held  in  check  in  certain  orchards  in  Michigan.  The  trees  usually 
die  quicker  from  little  peach  (about  three  years)  than  from  the 
yellows. 

Concerning  this  disease  Waite  (Rept.  Conn.  Pom.  Soc.  1908: 
64)  says :  "The  little  peach  resembles  yellows  in  many  respects, 
particularly  in  the  foliage  symptoms ;  and  yet  certain  of  its  symp- 
toms are  exactly  the  opposite,  namely,  those  of  the  fruit.  Fruit 
on  trees  affected  by  little  peach  is  undersized  and  belated  in 
ripening.  It  is  often  a  week,  or  two  weeks  or  more  belated.  Its 
size  may  be  only  slightly  reduced  in  mild  cases,  down  to  little  tiny 
peaches  less  than  three-fourths  of  an  inch  in  diameter.  Little 
peach  trees  rarely  throw  the  wiry  growth.  I  have  only  seen  it 
produced  where  they  were  cut  back,  or  on  very  vigorous  young 
trees.  It  is  rarely  bushy  and  prominent,  as  in  the  case  of  the 
yellows.  The  foliage  characters  of  the  little  peach  are  so  nearly 
like  peach  yellows  that  when  the  fruit  is  absent  and  no  wiry 
growth  occurs,  as  is  frequently  the  case  on  yellow  trees,  it  is 
impossible  to  distinguish  the  two  diseases." 

The  writer  is  inclined  to  believe  that  little  peach,  like  much  of 
our  so-called  yellows,  is  indirectly  due  to  weather  conditions, 
such  as  the  droughts  of  1907  and  1908,  and  possibly  to  winter 
injury.  At  least,  it  has  shown  up  most  prominently  since  the 
drought  of  1907,  and  Smith's  statement  that  the  fibrous  roots  of 
the  trees  seem  to  be  injured,  goes  along  very  well  with  the 
drought  theory.  See  article  relating  to  peach  yellows  and 
so-called  yellows,  later  in  this  Report. 

POPPY,  Papaver  sp. 

Bacterial  Spot?  During  the  past  two  seasons  the  writer 
has  noticed  the  leaves  on  poppies  in  his  yard  badly  spotted  from 
some  cause.  These  spots  are  dark  reddish-brown,  somewhat 
watery,  irregular,  and  about  one  to  three  millimeters  in  length, 
and  usually  are  quite  numerous.  An  examination  of  dried 
specimens,  collected  last  fall,  shows  these  diseased  spots  crowded 
with  bacteria,  which  appear  to  be  the  cause  of  the  trouble.     So 


NOTES    ON    FUNGOUS   DISEASES    FOR    I908.  87 1 

far  no  such  bacterial  disease  of  this  host  seems  to  have  been 
described,  so  that  before  a  positive  statement  can  be  given, 
cultures  and  inoculations  will  have  to  be  made. 

EADISH,  Raphanus  sativus. 

Spindling.  This  is  a  trouble  which  sometimes  appears  in 
radishes  grown  in  hotbeds,  where  they  have  not  been  watched 
closely  enough  after  they  germinated.  The  trouble  is  due  to 
too  great  heat  at  this  time,  so  that  the  radishes  grow  too  rapidly, 
forming  a  long  slender  hypocotyl,  often  two  or  three  inches  above 
the  ground.  Such  radishes  are  largely  worthless,  and  are  usually 
pulled  up  and  the  bed  reseeded,  as  the  bottoms  of  the  small 
turnip-shaped  radish  will  not  form  or  will  be  irregular  under 
such  conditions.  The  way  to  prevent  such  trouble  is  not  to  use 
the  beds  too  soon  after  making,  and  to  watch  them  carefully  to 
see  that  the  temperature  is  properly  controlled  by  ventilation,  so 
that  the  radishes  will  not  grow  too  rapidly  for  a  time  after  they 
break  through  the  ground. 

RHODODENDRON",  Rhododendron  maximum. 

Leaf  Spot,  Phyllosticta  maxima  E.  &  E.  This  is  found 
occasionally  on  leaves,  forming  reddish-brown  areas  (often 
grayish  with  flaking  away  of  the  epidermis)  of  greater  or  less 
fetent,  usually  at  the  margins  or  tips.  Other  fungi  sometimes 
occur  on  the  spots,  so  possibly  this  is  not  entirely  the  cause  of 
the  trouble. 

SUNFLOWER,  ORNAMENTAL,  Helianthiis  multiflorus. 

Powdery  Mildew,  Erysiphe  cichoracearum  DC.  This  forms 
a  whitish-gray,  mealy  coating  over  the  upper  surface  of  the 
leaves.  On  these  specimens,  collected  on  September  12th,  the 
perithecia  were  not  present. 

Rust,  Puccinia  Helianthi  Schw.  This  rust  was  found  on  the 
same  specimens  with  the  above  mildew,  but  was  confined  chiefly 
to  the  under  surface  of  the  leaves,  the  II  and  III  stages  showing 
as  numerous  minute,  dusty,  reddish  or  blackish  outbreaks. 
Apparently  the  rust  has  not  been  reported  often  on  this  host, 
though  on  the  various  wild  species  it  is  quite  common.  (See 
Report  of  1903,  p.  361.) 


872         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 


II.     PEACH  YELLOWS  AND  SO-CALLED  YELLOWS 

General  statement.  During  the  seasons  of  1907  and  1908 
peach  trees  in  Connecticut  have  shown  an  unusual  amount  of 
injury  variously  classed  as  yellows,  so-called  yellows,  little  peach, 
collar  girdle,  winter  injury  of  wood,  drought  injury,  leaf  fall, 
gummosis,  etc.  Some  persons  have  been  inclined  to  lump 
these  troubles  largely  into  so-called  "yellows,"  and  others  have 
made  very  nice  distinctions,  especially  as  to  cause,  apparently 
where  such  did  not  exist. 

There  is  no  question  that  there  has  been  an  unusual  amount  of 
typical  yellows  present,  such  as  shown  in  Plate  LXIX  b  (a 
photograph  of  a  peach  tree  made  by  Dr.  Britton  in  East  Haven 
in  1902),  and  there  is  likewise  no  question  that  much  of  the. 
so-called  yellows  has  not  been  typical.  For  instance,  many  of  the 
trees  cut  down  last  fall  as  suffering  from  yellows  bore  a  crop 
of  peaches  of  good  quality,  and  often  with  no  indication  of  the 
red  streaking  in  the  interior  which  is  taken  to  be  one  of  the  very 
first  signs  of  this  trouble.  What  the  writer  wishes  to  bring  out 
in  this  article  is  that  these  various  troubles  are  largely  the  result 
of  the  unusual  weather  conditions  that  have  prevailed  during  the 
past  seven  years.  That  secondary  causes,  such  as  germs  and 
enzyms,  may  have  afterward  entered  into  the  problem  and  pro- 
duced the  various  dififcrences  that  show  in  different  trees,  is  quit^ 
possible,  but  these  alone  we  do  not  believe  are  to  be  held 
responsible.  What  have  been  these  weather  conditions  and  their 
effects,  as  shown  by  our  observations  covering  this  entire  period, 
and  of  which  there  can  be  no  question?     They  are  as  follows: 

Relation  of  Peach  Troubles  to  Weather. 

Winter  injury  in  ipo2.  On  December  9,  1902,  after  a  very 
open  fall  in  which  late  growing  trees  had  no  chance  to  properly 
mature  their  wood,  there  came  a  sudden  drop  to  zero  weather. 
As  a  result  apple  and  peach  trees  in  the  nursery  and  those 
recently  set  out  in  the  orchards  had  their  wood  prematurely  killed 
or  badly  injured.  Specimens  were  sent  to  the  station  by  nursery- 
men immediately  after  this  injury,  and  the  writer  also  had 
abundant  opportunity  during  the  next  two  years  to  study  such 
trees   in  the   nurseries   and   orchards.     Such   trees    showed   the 


PEACH    YELLOWS   AND   SO-CALLED    YELLOWS.  873 

normally  white  wood  darkened  nearly  or  quite  up  to  the  bark, 
but  when  not  too  severely  injured,  the  next  year  a  small  annual 
growth  of  white  wood  was  formed  around  this.  (See  Plate  X  a, 
Rept.  1903.)  Trees  suffered  most  that  were  set  out  in  low 
places,  and  in  the  nurseries  where  the  trees  had  been  stimulated 
to  late  growth  by  forcing  them  with  chemical  fertilizers  and  late 
cultivation. , 

No  one  seemed  to  know  much  about  such  a  trouble,  even 
among  the  nurserymen ;  one  firm  built  a  large  storage  shed  the  next 
summer  to  avoid  future  trouble  to  the  season's  stock.  Some  of 
the  least  injured  of  these  trees  were  sold  the  following  year,  but 
where  complaint  was  made  that  they  died,  the  nurserymen  made 
good  the  loss.  In  other  cases  the  young  nursery  trees  were  cut 
back  near  to  the  ground  and  a  new  trunk  started.  In  some 
instances  such  trees  had  to  be  cut  back  again  the  next  year 
because  of  further  winter  injury.  We  have  seen  two  orchards 
set  out  by  nurserymen  from  these  twice  winter-injured  and  cut- 
back trees  which  the  past  year  have  gone  with  the  so-called 
yellows.  In  one  case  the  trees  showed  winter  injury  subsequent 
to  setting  the  orchard,  and  in  the  other  practically  none.  Now, 
we  hold  the  winter  injury,  the  severe  pruning  back,  and  the 
droughts  of  1907  and  1908  as  primarily  responsible  for  the 
decline  of  these  orchards,  rather  than  yellows. 

Severe  zvinter  of  igo^-04.  The  winter  of  1903-04  did  not  find 
the  trees  so  unprepared,  because  of  an  open  fall,  as  the  previous 
year,  yet  it  was  so  unusually  severe  that  even  greater  injury  was 
done.  This  was  especially  true  in  the  older  orchards.  Many 
trees  were  killed  outright  all  over  the  state.  Most  frequently  the 
injury  showed  in  the  wood,  which  was  blackened  to  the  snow 
line,  while  the  bark  and  roots  were  uninjured.  Severe  injury 
of  course  killed  the  cambium,  and  then  the  trees  were  past  any 
help.  This  injured  or  prematurely  killed  wood  undoubtedly  set 
up  unusual  chemical  activities  that  may  have  resulted  in  dele- 
terious enzyms  or  other  products  that  were  carried  in  time  to  the 
new  growth.  Anyway,  after  some  years  I  do  not  find  that  the 
sharp  demarcation  between  the  darkened  winter-injured  wood 
and  the  subsequent  growth  of  normal  white  wood  shows  as 
plainly  as  it  did  at  first. 

In  some  places,  often  depending  upon  low  elevation  or 
exposure  to  moist  winds,  parts  of,  or  even  whole  orchards,  were 


874         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

SO  severely  injured  that  they  were  taken  up.  Many  of  the  trees 
least  severely  injured  were  severely  pruned  back  and  new  growth 
started.  The  illustrations  on  Plate  LXVII  show  two  trees  that 
were  severely  injured  but  not  pruned  back  until  the  early  spring- 
of  1906;  one  of  the  trees  failed  to  respond,  but  the  other  made 
in  three  years  the  vigorous  growth  shown  in  the  illustration,  and 
in  1908  bore  a  fine  crop  of  fruit.  Such  trees,  however,  go  much 
quicker  than  trees  not  injured,  and  where  the  injury  was  severe, 
even  with  the  help  of  severe  pruning,  they  have  been  dying  from 
year  to  year,  often  from  yellows  or  so-called  yellows.  No  one 
has  disputed  the  winter  injury  to  the  trees  that  were  killed  out- 
right; but  with  the  trees  that  have  since  gone  into  decline,  the 
fact  that  they  were  thus  handicapped  has  been  overlooked  by 
many  who  attribute  this  whole  trouble  to  "yellows." 

Subsequent  winter  injuries.  Since  the  winter  of  1903-04  (as, 
for  instance,  in  1906),  there  has  been  some  further  injury,  chiefly 
to  the  young  twigs  and  buds,  but  nothing  nearly  so  severe  or 
unusual.  During  the  winter  of  1907-08,  however,  winter  injury 
from  collar  girdle  and  root  killing  was  unusually  evident, 
especially  where  the  ground  was  not  properly  drained  or  where 
there  was  no  mulch  of  snow  to  protect  the  base  of  the  trees  and 
the  roots. 

Droughts  of  ipo/  and  ipo8.  But  while  these  subsequent 
winters  have  not  been  so  severe,  certain  of  the  summers  have 
been,  especially  the  summers  of  1907  and  1908,  when  unusual 
droughts  prevailed.  In  1907  by  far  the  most  injury  resulted,  as 
the  dry  period  lasted  from  June  to  August,  when  the  rainfall  was 
less  than  half  that  of  the  average  year.  In  1908  the  drought  was 
broken  by  rains  in  midsummer,  which  lessened  the  otherwise 
severer  injury  that  would  have  resulted  from  the  unusual  early 
and  late  dry  spells. 

,  After  the  summer  drought  of  1907,  which  at  the  time  showed 
its  effect  on  all  vegetation,  came  the  moist  fall  weather,  and  in 
many  cases  this  set  up  a  late  growth  of  the  dormant  buds  on  the 
peaches.  The  yellow,  curled  leaves,  due  to  the  drought,  and  this 
premature  fall  growth  of  buds,  were  taken  even  by  some  experts 
to  be  the  first  symptoms  of  yellows.  That  such  persons  were 
mistaken  in  some  cases,  at  least,  was  demonstrated  with  certain 
nursery  trees  showing  these  signs  and  pronounced  typical 
yellows,  by  setting  them  out  by  themselves  and  keeping  them 


PEACH    YELLOWS   AND   SO-CALLED   YELLOWS.  875 

under  observation  the  following  year,  when  all  trace  of  the 
so-called  yellows  disappeared.  Likewise  certain  orchards  pro- 
nounced infected  with  yellows,  the  next  year  under  special  care 
showed  decided  improvement.  There  seems  to  be  little  doubt 
that  these  dry  seasons  injured  the  trees  partly  through  the  death 
of  the  fibrous  rootlets.  We  know  of  one  orchard  planted  with 
winter-injured  stock  and  showing  subsequent  winter  injury, 
situated  on  the  top  of  a  high,  very  rocky  hill,  where  all  attempts 
at  cultivation  merely  increased  the  loss  of  water  from  the  soil 
during  the  drought,  and  where  the  fibrous  rootlets  were  killed 
or  severely  injured.  No  wonder  this  orchard  has  since  dis- 
appeared because  of  the  unfavorable  environmental  conditions 
that  have  surrounded  it! 

Theories  Concerning  Yellows. 

Winter  injury  theory.  Now  from  the  above  we  do  not  wish  it 
to  be  understood  that  we  believe  that  the  yellows  never  can  occur 
on  trees  not  injured  by  unfavorable  weather  conditions.  It  is 
past  dispute  that  it  can  be  budded  into  healthy  trees,  and  there 
seems  to  be  some  reason  for  supposing  that  it  is  even  contagious, 
though  no  positive  proof  of  this  seems  to  exist.  What  we  do 
wish  to  offer  is  that  seasonal  injuries  are  the  starting  point  and 
main  factor  of  these  so-called  waves  of  yellows.  This  is  no  new 
theory.  William  Saunders,  of  the  U.  S.  Department  of  Agri- 
culture, writing  to  Penhallow  in  1883  (Bull.  Houghton  Farm 
III,  3:  53)  said:  "About  thirty  years  ago  I  came  to  the  conclu- 
sion that  this  disease  was  one  which  originated  from  frost  acting 
on  the  unripened  wood.  I  have  never  known  a  tree  to  have  the 
yellows  when  placed  in  conditions  where  the  wood  became  thor- 
oughly ripened  before  frost,  a  circumstance,  as  you  are  aware, 
which  never  occurs  in  the  Northern  States.  Any  application 
which  will  hasten  ripening  of  the  wood,  will,  therefore,  have  a 
tendency  to  ward  off  the  conditions  which  make  it  possible  for 
the  tree  to  show  yellows.  This  disease  is  to  be  seen  on  other 
plants  which  are  similarly  placed,  and  it  was  that  observation 
which  first  led  me  to  look  for  the  cause  of  peach  yellows  in  that 
direction." 

In  support  of  this  connection  between  yellows  and  winter 
injury,  we  present  the  following  points:  (i)  The  apparent  rela- 
tion of  the  present  unusual  development  of  yellows,  not  only  in 


876         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

Connecticut,  but  elsewhere,  to  the  very  severe  and  widespread 
winter  injuries  that  have  occurred  to  peaches  since  1902.  (2) 
The  fact  that  both  winter  injuries  and  yellows  come  in  unusual 
severity  at  irregular  periods,  and  the  seeming  fact  that  the  waves 
of  yellows  gradually  develop  some  time  after  these  severe 
winters,  often  not  reaching  full  development  for  some  years. 
Besides  the  present  case,  there  seems  to  have  been  some  relation 
between  the  severe  winter  of  1881  and  the  yellows  that  developed 
in  New  York,  Connecticut  and  Delaware  in  the  following  years. 
(3)  The  apparent  limitation  of  yellows  to  the  northern  part  of 
the  United  States  and  the  mountainous  regions  in  the  South, 
where  winter  injury  occurs.  (4)  The  fact  that  the  peach  is  now 
a  highly  developed  sensitive  plant,  as  compared  with  its  native 
condition,  and  is  grown  out  of  its  natural  climate,  and  so  is  more 
likely  to  succumb  to  unfavorable  environment. 

Potash  theory.  A  second  theory  regarding  the  cause  of 
yellows,  not  now  held  to  any  great  extent,  apparently,  was  that  of 
soil  exhaustion  of  the  food  elements  necessary  for  the  best 
development  of  the  peach,  Penhallow  came  to  this  conclusion, 
after  a  careful  survey  of  the  subject  from  all  points  of  view, 
basing  his  belief  largely  on  the  chemical  analyses  of  Dr.  Goess- 
man*  of  Massachusetts  which  showed  a  lack  of  potassium  oxide 
in  peach  yellow  fruit  and  wood.  (Jenkins  also  later  reported  a 
similar  result  in  this  state.)  Penhallow  advocated  fertilization 
with  chemical  fertilizers  of  which  muriate  of  potash  is  a  promi- 
nent constituent.  The  possible  lack  of  potash  in  the  diseased 
trees,  the  general  need  of  fruits  for  this  element,  and  its  easy 
exhaustion  from  the  soil,  all  are  facts  which  are  in  favor  of  <"Iie 
use  of  potash  fertilizers.  Hale  and  others  have  found  it  of 
benefit,  but  Erwin  F.  Smith's  extended  experiments  (U.  S.  Dept. 
Agr.,  Div.  Veg.  Path.,  Bull.  4.  1893)  have  shown  that  it  is  not 
a  cure  or  preventive  for  yellows,  and  presumably  its  depletion  in 
the  soil  is  not  the  cause.  Perhaps  its  value  can  be  well  summed 
up  in  the  words  of  Hale  (Rept.  Conn.  Bd.  Agr.,  1891,  p.  65), 
who  said:  "My  own  experience  has  been  that  trees  fertilized 
with  muriate  of  potash  and  given  the  same  treatment  as  other 
trees  to  which  it  was  not  applied  have  been  freer  from  the 
yellows,  have  lived  longer  and  produced  better  fruit,  although 


*  Smith  in  his  paper   (Bull.  4)    reports  analyses  at  variance , with  this 
idea. 


PEACH    YELLOWS   AND   SO-CALLED   YELLOWS.  877 

some  of  them  have  been  diseased,  than  trees  around  which  potash 
in  that  form  was  not  used  at  all  *  *  *  It  is  not  a  cure-all, 
but  it  is  to  a  certain  extent  a  check."  A  good  illustration  of  the 
effect  of  a  potash  fertilizer  on  a  peach  orchard  not  in  good  shape 
was  shown  in  the  case  of  one  of  Mr.  Lyman's  orchards  at  Middle- 
field  the  past  season.  The  year  before,  apparently  due  to  the 
drought,  the  orchard  was  in  such  shape  that  an  expert  pro- 
nounced it  an  incipient  case  of  yellows.  Mr.  Lyman  gave  it  a 
treatment  with  saltpeter  (potassium  nitrate),  with  the  result  that 
the  orchard  last  season  took  a  decided  step  forward  instead  of 
backward.  Of  course  if  the  trouble  really  was  yellows,  such 
improvement  will  probably  prove  of  only  temporary  benefit. 

Enzym  theory.  A  third  explanation  of  yellows  has  been  that  it 
is  a  physiological  disease  somewhat  of  the  nature  of  indigestion, 
due  to  derangement  of  the  chlorophyll  of  the  leaves,  as  is  seen  in 
variegated  plants.  Such  trouble  is  thought  to  be  brought  about 
by  the  presence  of  some  deleterious  enzym  in  the  plant,  and  it  is 
this  enzym,  when  carried  by  budding  from  diseased  to  healthy 
stock,  that  causes  the  yellows  to  develop  in  the  latter.  Smith 
(U.  S.  Dept.  Agr.  Farmers'  Bull.  17:  10.  1894)  and  Woods 
(U.  S.  Dept.  Agr.,  Bur.  PI.  Ind.  Bull.  18:  22.  1902)  were  the 
first  to  present  this  or  a  similar  theory,  though  they  did  not 
account  for  the  origin  of  the  deleterious  enzym.  This  theory, 
modified  by  the  belief  that  it  is  the  unfavorable  weather  condi- 
tions (winter  freezing  and  summer  drought)  that  are  directly 
responsible  for  the  development  of  the  injurious  enzyms  or 
toxins,  is  the  theory  held  by  the  writer.  (See  also  in  Rept.  Conn. 
Pom.  Soc.  1909,  Report  on  Fungous  Diseases  for  1908.) 

Germ  theory.  The  fourth  prominent  theory  to  account  for 
yellows  is  the  bacterial,  or  germ  theory.  This  was  probably  first 
advanced  by  Burrill.  Smith,  in  a  recent  conversation,  and 
Waite  (Rept.  Conn.  Pom.  Soc,  1908,  p.  59),  also,  seem  inclined 
to  this  view,  though  all  admit  that  nothing  definite  has 
yet  been  found  to  support  it.  The  chief  point  in  its  support  is 
the  supposed,  but  not  definitely  proven,  contagious  character  of 
yellows. 

Preventive  Measures. 
From  the  above  consideration  we  may  present  the  following 
precautionary  measures  for  the  -guidance  of  Connecticut  peach 
growers : 


878         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

(i)  Location.  Peach  orchards  should  be  planted  only  in  the 
southern  half  of  the  state,  preferably  not  too  close  to  the  Sound. 
Along  the  Connecticut  Valley  they  may  extend  farther  north 
than  the  center  of  the  state.  Low  lands  should  be  avoided,  and 
as  a  rule  only  the  higher  hills  selected,  where  the  exposure  is 
such  as  to  avoid  as  much  as  possible  moist  winds  in  winter  and 
early  development  of  the  buds  in  spring.  Good  drainage  is 
necessary  to  avoid  root  injuries. 

(2)  Inspection.  Only  the  best  nursery  stock  should  be  used, 
free  from  all  suspicion  of  winter  injury  or  yellows.  Winter 
injury  can  be  told  by  the  blackened  wood.  As  it  is  not  always 
possible  to  detect  yellows  in  nursery  trees,  the  young  orchard 
should  be  watched  during  the  first  few  years,  in  order  to 
promptly  remove  any  suspicious  trees,  for  it  is  generally  supposed 
that  yellows  is  contagious.  In  the  bearing  orchards,  also,  any 
tree  showing  signs  of  yellows  should  be  promptly  cut  down  and 
burned.  Such  trees  are  of  little  value  anyway,  and  it  is  best  to  be 
on  the  safe  side  of  the  question.  Such  is  also  the  practice  of 
good  orchardists  in  the  best  peach-growing  districts. 

(3)  FeHilization.  As  shown  above,  potash  is  a  very  neces- 
sary element  for  peach  growing,  and  so  fertilizers  should  be  well 
supplied  with  it.  Care,  however,  should  be  used  not  to  force 
trees  too  much,  especially  with  late  applications  of  commercial 
fertilizers.  This  is  especially  true  of  sodium  nitrate.  Such 
trees  are  apt  to  go  into  the  winter  with  the  wood  in  an  immature 
condition,  and  are  then  especially  subject  to  winter  injury. 

(4)  Cultivation.  Good  and  frequent  cultivation  during  the 
first  of  the  season  is  very  desirable,  but  after  midsummer  should 
be  discontinued,  since  late  cultivation,  like  late  applications  of 
fertilizers,  may  prevent  proper  maturity  of  the  wood.  Perhaps 
after  cultivation  is  over  it  will  be  well  in  some  cases  to  seed  down 
the  land  with  a  quick-growing  leguminous  cover  crop  which  can 
be  plowed  under  the  next  spring.  This  will  help  to  supply  the 
nitrogen,  and  also  give  more  or  less  protection  against  winter 
injury  to  the  roots,  especially  where  the  snow  blows  off  or  is 
lacking.  Green  (Ohio  Agr.  Exp.  Station  Bull.  157.  1904) 
found  in  the  study  of  winter  injury  to  peach  trees  in  Ohio  that 
where  the  trees  were  mulched  or  protected  by  crimson  clover,  or 
other  cover  crops,  root  injury  was  much  less.  A  mulch  of  earth 
thrown  up  around  the  younger  trees  in  the  fall  and  removed  in 
the  spring  also  seems  to  be  of  value  in  lessening  collar  girdle. 


CHESTNUT    BARK   DISEASE.  879 

III.     CHESTNUT  BARK  DISEASE,  Diaporthe  parasitica 

Murr. 

General  statement.  In  the  Report  for  1907,  p.  345,  this 
serious  trouble  of  chestnuts  was  briefly  described.  The  writer 
first  heard  of  the  chestnut  disease  in  1905,  through  an  article  in 
a  New  York  newspaper  which  discussed  a  serious  disease  of 
chestnuts  in  the  Zoological  Park.  Specimens  had  been  sent  to 
the  U.  S.  Department  of  Agriculture  at  Washington  for  identi- 
fication and  suggestions  for  control.  Flora  W.  Patterson 
reported  it  as  a  species  of  Cytospora  and  suggested  spraying  with 
Bordeaux  mixture. 

A  short  time  later,  Dr.  Murrill  of  the  New  York  Botanical 
Garden,  who  has  since  made  an  extended  study  of  the  fungus 
and  its  havoc,  sent  the  writer  specimens  of  diseased  chestnut 
bark  for  his  opinion  as  to  the  cause.  We  reported  the  presence 
of  a  Cytospora,  but  from  our  experience  with  similar  fungi  at 
that  time,  stated  that  we  believed  it  might  be  follojving  winter 
injury  to  the  trees  rather  than  be  the  direct  cause  of  the  trouble. 
Dr.  Murrill  later  found  the  Cytospora  to  be  the  conidial  stage 
of  an  ascomycetous  fungus  which  he  described  as  a  new  species, 
Diaporthe  parasitica.  In  his  first  articles  Dr.  Murrill  noted  that 
the  trouble  probably  resulted  in  part  from  winter  injury  to  the 
trees,  but  later  he  and  all  others  who  have  written  concerning 
the  disease  lay  the  responsibility  entirely  on  the  fungus. 

Through  the  kindness  of  Dr.  Murrill  the  writer  has  several 
times  visited  Bronx  Park,  where  great  damage  was  done,  and  has 
seen  something  of  his  experimental  work  with  the  fungus. 
Forest  Park,  Brooklyn,  was  also  visited  in  the  fall  of  1908,  and 
a  number  of  localities  in  Fairfield  and  New  Haven  counties,  this 
state,  have  been  especially  examined  both  by  the  writer  and  by 
Mr.  Hawes.  The  writer  has  not  aimed  to  make  a  special  study 
of  the  particular  fungus  ordinarily  associated  with  the  trouble, 
as  that  has  already  been  done  very  ably  by  Dr.  Murrill  (Jour. 
N.  Y.  Bot.  Card.  7:  143-153.  Je.  1906.  Ibid.  7:  203-11.  S. 
1906.  Ihid.  9:  23-30.  F.  1908.  Torreya  6:  186-9.  S.  1906). 
However,  our  extended  experience  since  1902  with  trees  of  all 
kinds  which  have  shown  various  unusual  troubles,  due  primarily 
to  seasonal  injuries,  does  not  permit  us  to  agree  entirely  with 
62 


88o         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

Dr.  Murrill,  and  apparently  Mr.  Metcalf,  that  this  trouble  is  due 
alone  to  the  fungus  Diaporthe  parasitica. 

General  character  of  the  disease.  In  the  vicinity  of  New  York 
City  the  disease  took  chestnut  trees  of  all  ages,  the  large  trees 
suffering  as  much  as  the  younger  trees  or  the  sprouts.  In  most 
places  there  the  trouble  has  now  made  a  pretty  clean  sweep,  so 
that  few  living,  or  at  least  healthy,  chestnut  trees  are  left.  But 
as  we  come  over  into  Connecticut,  the  injury  gradually 
diminishes,  being  as  yet  serious  only  in  Fairfield  County,  and 
growing  less  toward  its  northern  and  eastern  borders.  Here, 
though  many  large  trees  were  killed,  not  all  were  taken,  and  as 
we  go  toward  its  outer  limits  the  damage  is  only  to  the  chestnut 
sprouts  and  small  trees.  In  New  Haven  County  it  seems  to  be 
almost  entirely  the  sprout  growth  that  was  injured. 

Where  large  trees  are  infected,  they  begin  to  die  from  the  top, 
and  their  decline  is  gradual,  until  the  tree  is  killed  to  the  base. 
Whether  the  roots  of  such  trees  are  ultimately  killed  I  do  not 
know,  but  in  one  tree  examined  by  the  writer  at  Middlebury, 
while  the  trunk  was  dead  to  the  ground,  the  main  roots  did  not 
yet  show  injury.  This  at  least  proved  that  the  tree  was  not 
dying  as  the  result  of  root  injury,  unless  possibly  to  the  very 
small  fibrous  rootlets.  Sometimes  these  dead  trees  show  no 
fungus  growth,  but  usually  in  time  there  can  be  found  the  char- 
acteristic orange  or  chestnut-brown  pustules  of  this  fungus 
breaking  through  the  cracks  of  the  rough  bark,  being  developed 
gradually  lower  and  lower  down  the  tree.  The  tree  dies  because 
the  bark  and  cambium  are  killed,  but  the  fungus  does  not  develop 
into  the  wood  very  deeply. 

On  the  sprout  growth  and  younger  trees  with  smooth  bark, 
however,  the  trouble  shows  much  more  plainly  (see  Plate 
LXII  b)  through  cankered  areas  in  the  apparently  healthy  bark, 
and  these  frequently  completely  girdle  the  trunk  or  branches.  In 
late  fall  and  winter  the  fruiting  stage  of  the  fungus  shows  on 
these  as  small,  reddish-  or  chestnut-brown  cushions  thickly  break- 
ing through  the  bark.  It  is  these  cankered  areas  on  the  smooth 
bark  that  afford  the  best  evidence  that  the  trouble  is  entirely  due 
to  the  fungus.  Such  cankered  spots,  however,  usually  start  from 
a  winter-killed  twig  or  other  injury. 

General  distribution.  The  trouble  has  now  made  a  nearly 
clean  sweep  of  the  chestnut  trees  in  the  New  York  City  and 


CHESTNUT    BARK   DISEASE.  88 1 

Brooklyn  parks.  Dr.  Murrill  (Bull.  N.  Y.  Bot.  Gard.  6:  137. 
23  Mr.  1909)  says  concerning  Bronx  Park:  "All  of  the  chestnut 
trees  on  the  grounds  have  either  been  killed  or  seriously  damaged 
by  it."  Mr.  J.  J.  Levison,  arboriculturist  of  Brooklyn  parks, 
writes  concerning  Prospect  Park:  "We  have  removed  fourteen 
hundred  chestnuts,  practically  all  the  trees  of  that  species  but 
six."  He  also  reports  (Mycologia  i:  36.  Ja.  1909)  concern- 
ing Forest  Park  that  16,695  chestnut  trees  were  killed  in  350 
acres  of  Avoodland  there.  About  seven  thousand  of  these  were 
over  one  foot  in  diameter.  Mr.  John  Mickleborough  has  also 
made  a  somewhat  similar  report  (Conservation  14:  585-8.  N. 
1908)  concerning  the  condition  of  these  two  parks  and  else- 
where. He  estimates  the  total  damage  in  the  eastern  United 
States  as  at  least  ten  million  dollars. 

Metcalf,  of  the  U.  S.  Department  of  Agriculture  (Bur.  PL  Ind. 
Bull.  121®:  F.  1908),  gives  its  distribution  as  follows:  "The 
bark  disease  of  the  chestnut,  caused  by  the  fungus  Diaporthe 
parasitica  Murrill,  has  spread  rapidly  over  Long  Island,  where 
it  was  first  observed,  and  is  now  reported  from  Connecticut, 
Massachusetts,  Vermont,  New  York  as  far  north  as  Pough- 
keepsie.  New  Jersey,  Pennsylvania,  and  possibly  Delaware." 
Murrill  adds  Maryland,  and  possibly  Virginia  and  Washington, 
D.  C,  to  the  list. 

Distribution  in  Connecticut.  This  trouble  was  first  called  to 
our  attention  in  this  state  in  the  fall  of  1907  by  Mr.  F.  V.  Stevens 
of  Stamford,  Fairfield  County,  and  it  is  in  this  county,  which  is 
in  the  southwest  part  of  the  state,  next  New  York  and  the  Sound, 
where  the  chief  injury  has  occurred.  The  disease  has  been 
found  also  in  New  Haven  County,  which  is  on  the  Sound  next  to 
Fairfield,  but  it  occurs  here  only  on  the  sprout  growth,  and  not 
usually  doing  any  serious  damage  as  yet.  Outside  of  these  two 
counties  we  do  not  know  of  the  presence  of  the  disease,  as  deter- 
mined by  the  examination  of  specimens,  though  inquiries  have 
come  concerning  it  from  Willimantic  and  Pom  fret  Center,  in 
Windham  County. 

Mr.  Robert  T.  Morris  (Conservation  15:  226.  Ap.  1909) 
has  recently  called  attention  to  the  serious  damage  done  near 
Stamford  and  Greenwich,  and  states  that  unless  soon  cut,  the 
larsre  trees  will  be  of  little  value  for  lumber.     Because  of  the 


882         CONNECTICUT  EXPERIMENT  STATION  REPORT,   1907-I908. 

glut  on  the  market,  they  are  of  little  or  no  value  for  cordwood  at 
present. 

In  New  Haven  County  the  disease  has  been  reported  in  the 
following  places :  In  the  vicinity  of  New  Haven  the  writer  has 
found  only  a  few  specimens,  with  no  damage  whatever; — at 
Morris  Cove,  in  a  low  grove,  one  or  two  sprouts  were  found  with 
large  cankers  in  fruiting  condition;  in  Westville,  along  Beaver 
Creek,  a  few  small  trees  were  found  with  small  cankers  in  the 
otherwise  healthy  bark,  but  no  fruiting  pustules  except  in  one 
case.  These  cankered  spots  were  almost  all  on  the  south  side 
of  the  trees. 

W.  A.  Henry  sent  specimens  from  Wallingford,  where  he  says 
that  "many  sprouts  show  the  disease,  though  none  are  yet  dead." 

We  are  indebted  to  Newton  J.  Peck  of  Woodbridge  for  the 
specimen  shown  in  the  illustration,  Plate  LXH  b.  This  was  on 
an  eight-year-old  sprout  tree.  Mr.  Peck  says  that  only  the  sprout 
growth  is  affected  in  Woodbridge,  and  that  he  has  noticed  the 
trouble  there  for  four  or  five  years.  With  Mr.  Filley,  the  acting 
Forester,  we  recently  (April,  1909)  visited  Mr.  Peck's  woods  and 
also  others  in  Woodbridge,  and  found  considerable  of  the  fungus 
present,  but  almost  all  of  it  on  small  sprout  growth  or  small  trees. 
We  saw  many  cankers,  often  quite  small,  as  yet  showing  no  signs 
of  the  fungus ;  and  by  far  the  larger  part  of  these  were  on  the 
south  or  southwest  side  of  the  trees. 

W.  M.  Shepardson  of  Middlebury  reported  the  disease  in  that 
region,  and  the  writer  on  a  visit  there  found  the  fungus  in  two 
difllerent  woods.  The  situation  here  threw  more  light  on  the 
relation  to  weather  conditions.  On  a  dry  hill  on  the  Whittemore 
estate,  many  of  the  trees,  oaks  as  well  as  chestnuts,  showed  that 
they  were  not  in  prime  condition,  especially  their  bark.  Some 
few  were  dead,  and  others  had  dead  bark  on  one  side  of  the  tree, 
but  there  was  no  evidence  of  the  fungus.  There  is  little  question 
but  that  here  the  droughts  of  1907  and  1908,  especially  of  the 
former  year,  had  seriously  injured  the  trees.  On  a  low  spot  in 
another  grove,  owned  by  Mr.  Shepardson,  over  half  the  trees 
were  injured  or  dead.  While  many  of  them  showed  character- 
istic Diaporthe  cankers,  others  showed  growths  of  different 
fungi,  and  some  had  no  fungous  growth  at  all !  It  looked  to  the 
writer  as  if  winter  injury  and  drought  might  just  as  well  be 


CHESTNUT    BARK   DISEASE.  OS  3 

given  the  responsibility  for  the  trouble  here  as  the  bark  disease 
fungus. 

Mr.  Hawley,  of  the  Yale  Forest  School,  has  reported  the  fun- 
gus common  in  the  woods  of  the  Water  Company  near  Ansonia. 
Dr.  Graves,  of  the  Yale  Bot.  Dept.,  found  specimens  near  the 
North  Branford  line  on  the  road  to  Twin  Lakes.  Mr.  Metzger 
reports  a  few  infected  sprouts  in  his  woods  at  Mt.  Carmel.  No 
doubt  other  infected  regions  occur  besides. those  given. 

In  Fairfield  County,  the  writer  has  examined  forests  near 
Stamford  and  Danbury.  At  the  former  place,  due  to  the  kind- 
ness of  P.  V.  Stevens,  the  writer  and  Mr.  Hawes,  in  April,  1908, 
got  a  very  good  idea  of  the  damage  done  in  one  of  the  most 
seriously  affected  districts  in  the  state.  This  examination  gave 
the  writer  his  first  evidence  of  possible  relation  to  winter  injury. 
In  one  place  chestnut  sprouts  showing  signs  of  winter  injury 
(indicated  by  blackened  wood)  were  found  on  the  border  of  an 
old  orchard  that  also  showed  the  same  trouble.  In  cutting 
through  the  diseased  sprouts,  nearly  all  showed  this  dark  wood 
back  about  four  years,  when  the  severe  winter  of  1903-04  did 
much  damage  to  trees  of  all  kinds.  Of  course  it  is  not  always 
possible  after  several  years  to  distinguish  between  winter-injured 
wood  and  the  normally  colored  heartwood,  but  in  our  opinion  the 
dark  color  of  the  inner  wood  of  the  sprouts  (see  Plate  LXII  a) 
as  seen  almost  everywhere  is  too  close  to  and  sharply  marked  off 
from  the  sapwood  to  be  natural. 

In  order  to  determine  if  this  disease  was  contagious,  the  writer 
had  Mr.  Hawes  send  Mr.  Stevens  one  hundred  small  healthy 
chestnut  trees  from  the  state  nursery  at  Rainbow.  These  were 
set  out  among  the  diseased  trees  late  last  spring.  In  a  recent 
letter  Mr.  Stevens  states  that  these  trees  as  yet  show  no  sign  of 
the  fungus,  and  are  all  living  except  a  few  that  died  when  set  out. 
He  also  writes  regarding  sprouts  showing  the  disease:  "All  the 
sprouts  from  the  cut  of  1906  were  very  badly  infected,  in  fact, 
seventy-five  per  cent,  of  the  season's  sprouts  on  our  place  and 
elsewhere  in  the  near  vicinity  are  a  total  loss,  but  I  have  not 
found  a  single  sprout  of  the  cutting  of  the  winter  of  1907  that 
shows  the  least  infection,  although  I  have  spent  considerable  time 
looking  over  the  woodlands  in  our  section  of  the  state."  This 
condition  might  be  explained  by  the  fact  that  the  drought  of  1907 


884         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

was  unusually  hard  on  the  sprout  growth  of  that  year,  or  possibly 
by  the  fact  that  the  sprouts  of  1908  have  had  only  one  season 
yet  for  infection,  as  compared  with  two  for  the  others. 

At  Danbury  the  writer  did  not  get  into  the  worst  infected 
woods,  but  the  few  diseased  trees  examined  showed  chiefly  small, 
reddish-brown  cankered  spots  on  the  smooth  greenish  bark,  much 
like  what  winter  injury  will  produce  on  pear  and  other  fruit  trees, 
and  which  Sorauer  attributes  to  winter  injury  on  various  trees 
in  Europe.  These  cankered  spots  usually  had  no  fungous  growth 
on  them,  and  frequently  were  split  through  the  center,  but  in 
some  few  cases  the  injury  seemed  to  have  been  grown  over.  In 
one  specimen  brought  back,  that  at  the  time  was  taken  for  the 
Diaporthe  fungus,  it  was  found  on  closer  examination  to  be  a 
species  of  Discomycetes,  a  species  of  Dermatea,  as  determined 
by  E.  J.  Durand.  The  impression  gained  here  was  that  these 
cankered  spots  might  have  resulted  from  winter  injury,  as  they 
were  most  frequently  found  on  the  southwest  side. 

Mr.  Hawes,  in  his  recent  forest  survey  of  Fairfield  County, 
had  his  assistants,  Messrs.  Moon  and  Hodgson,  make  notes  in 
each  town  on  the  prevalence  of  the  chestnut  disease.  I  am 
indebted  to  Mr.  Hawes  for  the  following  notes  taken  from  their 
reports:  "As  I"  (F.  F.  Moon)  "came  eastward  from  Stamford, 
where  the  effects  were  the  worst,  the  number  of  infected  trees 
decreased  and  the  size  and  age  as  well.  In  the  last  three  towns 
(Fairfield,  Bridgeport,  and  Stratford)  the  infected  trees  seem  to 
be  almost  wholly  young  sprouts  along  the  road,  while  chestnut 
sprouts  in  the  center  of  the  stand  seem  to  be  free  from  the 
fungous  disease."  The  record  for  the  different  towns  in  Fairfield 
County  is  as  follows : 

Bethel.  "Disease  spread  over  whole  town  and  in  a  good  many 
cases  has  done  a  good  deal  of  damage." 

Bridgeport.  "A  few  cases  of  disease  in  open  grown  trees  along 
road." 

Brookfield.  "Disease  is-  scattered  over  town  here  and  there,  but 
not  doing  as  much  damage  as  further  west." 

Danbur3^  "The  chestnut  bark  disease  has  spread  from  New 
York  State  into  this  town,  all  through  its  woodlands,  and  into 
adjoining  towns.  The  affected  trees  are  more  numerous  near  the 
New  York  line,  but  they  are  in  good  numbers  throughout  the  town. 
Upon  examining  a  good  many  trees  I  find  that  most  of  the  diseased 
branches  and  trees  are  discovered  at  a  point  near  a  wound,  scar, 
or  crack.  In  the  crotch  of  two  limbs  which  have  slightly  cracked 
apart  seems  to  be  a  favorable  place  for  the  fungus  to  enter." 

Darien.  "The  disease  has  its  victims,  but  not  over  ten  per  cent. 
show  the  red  branch  of  distress,  and  very  few  are  killed." 


CHESTNUT    BARK   DISEASE.  885 

Easton.     "Disease  scattered  lightly  over  most  of  the  town." 

Fairfield.  "Only  small  per  cent,  of  trees  infected  with  chestnut 
bark  disease." 

Greenwich.  "Disease  has  infected  fully  forty  per  cent,  of  the 
trees,  but  has  not  killed  many  in  the  town.  Most  of  the  trees  have 
one  or  two  branches  affected,  but  as  far  as  any  serious  injury  is 
concerned  it  does  not  seem  anywhere  nearly  so  grave  as  in 
Stamford." 

Huntington.     "No  chestnut  bark  disease  reported." 

Monroe.  "Town  at  present  is  not  badly  infested  by  the  disease 
except  in  south  central  portion,  where  there  are  a  few  very  badly 
damaged  sprout  stands." 

New  Canaan.  "Disease  found  here,  but  not  over  ten  to  fifteen 
per  cent,  of  the  trees  are  infected,  and  these  only  slightly,  not  many 
dead  trees  being  seen." 

New  Fairfield.  "A  few  chestnuts  along  western  boundary  are 
affected  with  the  disease." 

Newtown.  "Bark  disease  has  appeared  only  on  scattered  trees 
along  western  boundary.  It  is  quite  certain  that  the  town  will  be 
infected  badly  with  it  next  year  if  the  present  rate  of  spreading 
continues." 

Norwalk.  "Disease  is  found  here,  but  not  to  such  a  great  extent 
as  further  down  the  coast.  It  seems  to  diminish  as  one  comes 
eastward.  From  ten  to  fifteen  per  cent,  of  trees  infected.  Few 
have  been  cut." 

Redding.  "Disease  is  spread  over  whole  town,  but  is  not  so  bad 
in  eastern  part." 

Ridgefield.  "Disease  has  spread  over  entire  town,  and  in  some 
cases  the  trees  are  infected  quite  badly,  though  only  a  few  trees 
killed." 

Sherman.  "Chestnut  bark  disease  appearing  in  western  part  of 
township." 

Stamford.  "Estimated  that  fifty  to  sixty  per  cent,  of  all  chestnut 
trees  in  township  are  infected  by  chestnut  bark  disease,  and  probably 
five  per  cent,  killed.  Conditions  especially  bad  in  northern  part  of 
town." 

Stratford.  "No  signs  of  any  disease  barring  a  few  cases  of 
Diaporthe,  which  seem  to  occur  chiefly  on  roadside  trees." 

Trumbull.  "Chestnut  bark  disease  has  not  as  yet  done  much 
damage.  Only  a  few  scattered  trees  noticed  that  were  attacked 
by  it." 

Westport.  "Trees  infected  by  chestnut  bark  disease  estimated  at 
five  to  ten  per  cent." 

Weston.  "Chestnut  bark  disease  is  generally  distributed  over 
town." 

Wilton.  "The  disease  is  found  here  but  not  so  much  of  it  as  in 
Stamford.  Not  over  fifteen  per  cent,  of  the  trees  infected,  and 
not  over  two  or  three  per  cent,  killed." 

The  fungous  agent.  Whether  or  not  the  fungus  always 
develops  its  fruiting  stage  in  the  cankers  the  first  year,  I  cannot 
state.  If  it  does  not,  then  this  fungus,  rather  than  winter  injury, 
might  explain  the  numerous  cankers  seen  without  any  fruiting 
pustules  whatever.  On  some,  however,  the  small  fruiting 
cushions  or  pustules,  much  like  lenticels  in  appearance  at  first, 
are  to  be  found  developing  during  the  summer,  but  apparently 


886         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

not  before  September  does  their  spore  stage  appear  to  any  extent. 
At  first  these  pustules  are  light  orange-brown,  but  by  winter 
become  dark  chestnut-brown.  They  are  composed  of  fungous 
threads  and  plant  cells.  The  fungus  has  two  spore  stages,  both 
of  which  develop  in  these  pustules. 

The  Cytospora  spore  stage  appears  usually  during  the  fall,  and 
can  be  found  more  or  less  abundant  until  late  spring.  In  cavities 
which  appear  in  these  pustules,  certain  slender  fungous  threads 
produce  on  their  extremities  very  minute  oblong  spores  in  great 
abundance.  These  ooze  to  the  surface,  under  moist  conditions, 
as  minute  tendrils  or  globules.  One  can  easily  see  that  because 
of  their  enormous  production,  they  would,  when  washed  by  rains 
over  the  tree,  soon  infect  it  badly,  if  entrance  was  readily  gained ; 
or  if  carried  by  insects,  birds,  or  the  wind  to  other  trees,  how  the 
disease  would  rapidly  spread. 

Usually,  along  the  latter  part  of  December,  the  second  or 
winter  spore  stage  reaches  its  maturity.  These  spores  are 
formed  in  special  small  spherical  receptacles,  to  be  made  out  with 
a  hand  lens,  something  like  light-colored  insect  eggs,  down  in 
the  tissue  at  the  base  of  the  pustule  and  around  its  margin. 
These  spore  receptacles  open  to  the  exterior  by  long  slender  necks 
that  run  from  the  receptacle  through  the  pustule.  These  necks 
can  be  seen  as  small  black  specks  on  the  surface,  or  in  cross  sec- 
tion of  the  pustule  when  in  their  prime.  The  receptacles  are 
filled  with  spore  sacs  (or  asci),  and  each  sac  has  eight  oval  to 
oblong  spores  arranged  within  it,  usually  in  a  single  row.  These 
spores  are  hyaline,  and  are  divided  at  the  center  (often  slightly 
constricted  there)  by  a  cross  wall  into  two  cells.  These  spores 
are  also  shed  out  of  the  cushions  during  the  late  winter  and  early 
spring,  so  that  finally  the  pustules  gradually  disappear,  leaving 
small  cavities  in  the  bark. 

With  care,  artificial  cultures  of  the  fungus  can  be  obtained  by 
taking  tissue  from  the  inside  of  cankers  in  the  early  stage  of 
their  development.  Such  cultures  of  the  fungus  on  Lima  bean 
agar  at  first  show  a  growth  of  whitish  threads,  but  with  the 
development  of  the  spore  stage  the  growth  gradually  changes  to 
a  bright  orange.  The  threads  form  a  rather  hard  crust  on  the 
surface  of  the  medium,  and  in  this  the  Cytospora  fruiting  stage 
develops  as  numerous  small  elevations.  The  spores,  after 
maturity,  ooze  out  on  the  pustules  as  lemon-yellow  drops,  which 


CHESTNUT    BARK   DISEASE.  887 

later  become  light  chestnut-brown  in  color.  The  asco-stage  did 
not  develop,  and  I  believe  Murrill  has  not  obtained  it  in  his 
cultures  on  various  other  media. 

The  writer  has  made  no  infection  experiments.  Murrill, 
however,  found  the  fungus  (in  his  inoculation  tests)  to  be  a 
wound  parasite,  but  after  it  once  gained  entrance  it  killed  the 
invaded  tissues  and  eventually  the  young  inoculated  trees. 

Relation  to  weather.  From  the  preceding  account  one  can 
readily  see  that  the  writer  believes  that  the  fungus  alone  is  not 
entirely  responsible  for  the  havoc  that  has  been  wrought  to  the 
chestnut  trees  during  the  past  few  years.  Winter  injury  in 
1903-04,  aggravated  by  the  droughts,  especially  that  of  1907,  we 
believe  to  have  been  important  factors  in  handicapping  the  trees 
so  that  the  way  was  opened  for  further  serious  injury  by  the 
fungus.  An  account  of  the  unusual  weather  conditions  that  have 
prevailed  here  since  1902  is  given  in  the  article  relating  to  peach 
yellows  and  so-called  yellows.  We  hold  that  these  winter  and 
drought  injuries  have  affected  chestnut  trees  as  follows: 

(i)  Probably  in  some  cases  trees  died  outright  from  winter 
killing  of  the  roots.  In  such  cases  no  sprout  growth  would 
result. 

(2)  Serious  injury  occurred  to  the  sapwood,  changing  it  pre- 
maturely into  heartwood,  and  thereby  greatly  reducing  the 
capacity  for  carrying  water  to  the  leaves.  Some  sprouts,  due  to 
the  droughts,  now  show  only  two  annual  rings  of  normal  white 
wood,  but  most  of  them  four  or  five,  with  a  sharp  demarcation 
between  the  white  and  colored  wood  indicating  possible  winter 
injury  in  1903-04, 

(3)  Numerous  cankered  areas  show  in  the  smooth  bark 
(often  without  any  fruiting  stage  of  the  fungus  on  these 
sprouts),  and  in  such  cases  these  are  chiefly  on  the  south  or 
southwest  side  of  the  trunk.  These  cankers  often  crack  open, 
offering  ready  entrance  for  the  fungus.  Sometimes  they  heal 
over,  or  are  not  deep  enough  to  cause  subsequent  injury. 

(4)  Numerous  branches  and  twigs  have  been  winter  killed 
on  otherwise  healthy  trees. 

(5)  Injury  probably  occurred  to  the  fibrous  rootlets  from  the 
droughts,  especially  on  rocky  knolls  and  hills,  in  1907. 

We  give  below  briefly  our  reasons  for  believing  that  weather 
conditions  are  partially  responsible  for  the  chestnut  disease. 


888         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

(i)  The  chestnut  disease  was  first  noticed  soon  after  the 
winter  of  1903-04.  Its  appearance  was  sudden  and  widespread, 
and  winter  injuries  rather  than  fungous  troubles  show  up  in  this 
way.  Since  its  appearance  possibly  it  has  spread  further,  but 
this  may  be  more  apparent  than  real,  since  discussion  of  the 
disease  has  caused  persons  to  look  for  it  in  places  where  it  was 
not  looked  for  before. 

(2)  This  trouble  has  gone  over  areas  with  greater  total 
destructiveness  than  any  purely  fungous  disease,  especially  of 
trees,  that  we  have  ever  seen  or  heard  of,  and  our  experience  has 
not  been  a  limited  one.  We  have  known  of  winter  injuries  in 
peach  orchards,  however,  just  as  severe,  and  both  of  these  trees 
are  here  near  their  northern  limit. 

(3)  The  nature  of  the  fungus  is  not  such  as  to  place  it  among 
the  virulent  parasitic  forms.  Murrill  found  it  a  wound  parasite, 
and  wound  parasites  are  rarely,  if  ever,  so  aggressive  as  to  totally 
destroy  their  hosts.  We  have  seen  cankers  in  apple  trees  pro- 
duced, without  doubt,  by  winter  injury  in  1903-04,  very  similar 
to  the  cankers  of  chestnut.  On  some  of  these  cankers  we  found 
a  Cytospora  fungus  which  at  first  we  thought  might  have  caused 
them.  We  have  also  found  Cytospora  fungi  on  twigs  of  other 
trees  killed  by  winter  injury.  The  genus  Diaporthe  is  made  up 
almost  entirely  of  saprophytic  species,  some  of  which  occur  on 
chestnut.  We  are  not  yet  sure  that  Diaporthe  parasitica  has  not 
been  collected  before  under  some  other  name.  Professor  Farlow 
calls  our  attention  to  the  fact  that  it  comes  more  naturally  under 
the  genus  Endothia,  and  is  closely  related  to  E.  gyrosa.  In 
deThiimen's  Myc.  Uni.  No.  769  is  a  specimen  under  this  name  on 
Castanea  vesca  collected  by  Saccardo  in  Italy  in  1876,  whose 
Cytospora  stage  (the  only  stage  showing  in  our  specimen)  seems 
quite  like  that  of  our  chestnut  fungus.  Rehm  (Ann.  Myc.  5 :  210. 
1907)  has  placed  D.  parasitica  under  the  genus  Valsonectria. 

(4)  The  distribution  of  the  injury  shows  that  the  vicinity  of 
New  York  City  was  the  center  of  the  trouble,  which  gradually 
lessens  in  severity  as  we  go  away  from  there  and  the  Sound, 
except  perhaps,  as  it  heads  up  the  Hudson  and  Housatonic 
Rivers.  Now  this  means  either  that  the  disease  is  spreading 
from  this  center,  or  that  this  region,  due  to  soil  or  atmospheric 
conditions,  sustained  severer  injury  to  the  chestnuts  during  the 
severe  winter  of   1903-04.     If  due  to  the   former,  why,  in  so 


CHESTNUT    BARK   DISEASE.  889 

distant  a  locality  as  Woodbridge,  New  Haven  County,  where  the 
disease  has  been  known  for  four  or  five  years  (as  long  as  in  New 
York)  has  not  the  disease  spread  to  the  old  chestnut  trees  and 
worked  similar  havoc  ? 

(5)  While  of  the  forest  trees  the  chestnut  has  suffered  far 
more  than  others,  especially  in  the  regions  indicated,  yet  in  both 
Massachusetts  and  Connecticut  during  the  past  few  years  Dr. 
Stone,  of  the  Amherst  Experiment  Station,  and  the  writer,  have 
had  called  to  their  attention  numerous  cases  of  trees  killed  or 
injured,  as  we  believe,  by  the  unfavorable  weather  conditions 
since  1902.  Dr.  Stone,  in  a  recent  letter,  says:  "All  through  this 
region  the  winter  of  1903-04  caused  a  great  deal  of  injury  to  a 
large  number  of  trees.  The  red  maples  have  been  dying  by  the 
hundreds  here,  due  to  root  killing,  and  I  have  seen  a  great  many 
oaks  and  large  elms  four  or  five  feet  in  diameter  injured  at  that 
time,  although  their  death  may  not  occur  until  three  or  four  years 
afterward.  It  is  interesting  to  note,  in  the  diagnosis  of  trees, 
of  which  I  do  a  great  deal,  that  the  injury  can  be  traced  back- 
wards four  or  five  years." 

The  writer  has  frequently  called  attention  in  his  previous 
reports  (Repts.  1903,  pp.  280,  303,  324,  328,  341,  351 ;  1904,  pp. 
312,  323,  326,  327;  1906,  pp.  310,  317,  320;  1907,  pp.  353,  360) 
to  winter  injuries  of  apple,  grape,  Koelreuteria,  peach,  privet, 
white  pine,  raspberry,  and  sycamore.  In  a  number  of  cases 
these  troubles  were  afterwards  complicated  with  fungous 
growths  that  to  those  unacquainted  with  the  conditions  would 
lead  them  to  beHeve  the  fungus  the  only  cause  of  the  trouble. 
The  past  year  we  have  also  seen  numerous  red  maples,  as 
mentioned  by  Stone,  that  seemed  to  be  dying  from  the  effects  of 
winter  and  drought  injuries.  We  do  not  include  the  elm  here 
because  it  is  difficult  to  determine  whether  or  not  the  elm  leaf 
beetle  has  been  entirely  responsible  for  the  death  of  many  of 
these  trees  which  have  died  in  recent  years. 

(6)  As  we  showed  in  a  previous  article,  chestnuts  have  been 
subject  to  severe  injuries  of  unknown  cause  in  the  past,  and 
have  not  been  annihilated  thereby.  The  cause  of  their  dying  was 
not  made  evident  at  the  time. 

Future  outlook.  If  the  chestnut  disease  is  due  alone  to  the 
Diaporthe  fungus,  as  Murrill  and  others  now  believe,  then  it 
seems  quite  likely  that  Metcalf  is  correct  in  his  statement  that 


890         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

unless  something  intervenes,  it  means  the  destruction  of  all  the 
chestnuts  in  the  Atlantic  States.  But  both  Murrill  and  Metcalf 
are  puzzled  to  explain  the  sudden  and  devastating  attack  of  the 
fungus.  The  latter  has  suggested  that  possibly  the  fungus  is  an 
importation  from  Japan,  and  that,  while  it  is  comparatively 
harmless  to  the  Japanese  species,  on  our  native  species  it  found 
a  host  upon  which  it  developed  with  unusual  virulence.  Murrill, 
however,  has  shown  the  writer  a  Japanese  chestnut  upon  which 
the  disease  was  as  aggressive  as  on  the  native  species.  He 
thinks  that  the  fungus  is  a  native  species  that  has  by  some  means 
acquired  unusual  virulence.  To  the  writer  neither  of  these 
theories  explains  the  situation  so  well  as  the  winter-drought 
explanation,  which  is  not  entirely  theoretical,  at  least. 

It  means  much  to  the  Connecticut  owners  of  forest  land 
whether  or  not  this  disease  is  due  alone  to  the  fungus  or  is  due 
in  part  to  seasonal  injuries.  In  the  former  case  they  may  expect 
that  they  are  just  beginning  to  see  the  results  of  a  devastating 
agent.  In  the  latter  case,  the  writer  believes  that  the  trouble  is 
now  probably  about  at  the  height  of  its  development,  so  that  not 
much  additional  harm  may  be  expected,  especially  if  the  follow- 
ing summer  or  two  prove  reasonably  moist  and  the  winters  are 
normal.  No  efficacious  treatment  for  the  prevention  of  the 
trouble  has  yet  been  found,  though  spraying,  pruning  and 
burning  of  infected  trees  have  been  advocated. 


ARTIFICIAL    CULTURES   OF   PHYTOPHTHORA,  89 1 

IV.    ARTIFICIAL  CULTURES  OF  PHYTOPHTHORA, 
WITH  SPECIAL  REFERENCE  TO  OOSPORES. 

General  Consideration. 

Previous  zvork.  The  downy  mildews  (Peronosporales)  have 
not,  to  the  writer's  knowledge,  been  grown  in  pure  artificial 
cultures,  with  the  exception  of  the  genus  Phytophthora.  Matru- 
chot  and  Molliard  of  France  (Bull.  Soc.  Myc.  Fr.  i6:  209-10. 
1900.  Ann  Myc.  i:  540-3.  1903)  were  the  first  to  grow  the 
potato  blight  fungus,  Phytophthora  infesians,  in  such  cultures, 
and  the  writer  (Ann.  Rept.  Conn.  Exp.  Station,  1905:  317-21) 
was  the  first  one  in  this  country  to  report  somewhat  similar 
results.  Jones  and  Giddings  of  Vermont  (Science  29:  271.  F. 
1909)  have  also  in  recent  years  been  working  along  this  line. 
J.  van  Breda  de  Haan  (Mededeel.  Uit's  Lands.  Plantentuim  XV. 
1896),  according  to  Matruchot  and  Molliard,  has  made  cultures 
of  the  mildew  of  tobacco,  Phytophthora  Nicotianae,  but  the 
writer  has  not  seen  this  publication.  The  writer  {loc.  cit.  p.  296), 
at  the  same  time  with  his  work  on  the  potato  mildew,  also  gave 
the  results  of  artificial  cultures  of  the  Lima  bean  mildew, 
Phytophthora  Phaseoli.  These  references  apparently  include 
most  of  the  work  that  has  been  done  along  this  line. 

This  method  of  attack  admits  of  a  more  thorough  study  of  the 
life  history  of  these  mildews.  All  of  these  fungi  are  supposed 
to  possess  two  spore  stages  in  their  life  cycle,  one  asexual  spores, 
conidia,  and  the  other  sexual  spores,  called  oogonia.  The 
oogonia,  however,  are  not  usually  produced  very  abundantly  or 
frequently,  and  so  are  rarely  found.  In  fact,  for  some  of  the 
species  they  have  never  been  discovered.  This  has  been  the  case 
with  the  potato  mildew;  and  unfortunately  the  artificial  cultures 
did  not  throw  any  further  light  on  this  stage,  as  none  of  the 
investigators  obtained  them.  With  the  Lima  bean,  however,  the 
writer,  in  his  first  investigations,  obtained  these  spores  somewhat 
in  moderation  in  the  artificial  cultures.  They  had  only  recently 
been  found  in  nature. 

The  results  of  the  writer  in  obtaining  the  oospores  of  the 
Lima  bean  mildew  in  artificial  cultures,  but  not  those  of  the 
potato,  together  with  other  considerations,  led  him  to  advance 
the  theory  that  with  this  group  of  fungi  there  might  exist  distinct 


892         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

sexual  strains  of  mycelia.  In  this  case  it  would  be  necessary  to 
have  both  strains  of  mycelia  present  for  the  formation  of  the 
oospores.  A  somewhat  similar  condition  had  been  recently 
found  for  certain  species  of  the  related  group  of  Mucorales,  by 
Blakeslee.  In  our  work  at  that  time  this  phase  of  the  subject 
was  tried  to  a  limited  extent  with  the  few  cultures  on  hand,  but 
nothing  very  definite  was  determined. 

In  our  previous  cultural  work  the  media  found  most  successful 
for  growing  these  fungi  were  living  plugs  of  potato,  cut  by 
aseptic  methods  and  placed  on  moist  cotton  in  a  sterilized  test 
tube;  living  Lima  beans,  taken  from  unbroken  pods  in  the  same 
way;  corn  meal,  mixed  with  water  or  various  juices,  etc.;  and 
potato,  or  pumpkin  juice,  agar.  While  the  fungi  grew  on  these 
media,  there  were  certain  drawbacks  for  each  that  made  it  rather 
difficult  to  obtain  pure  cultures  that  were  easily  renewed  and 
made  vigorous  growths. 

Present  work.  Last  fall  we  had  opportunity  to  obtain  further 
cultures  of  both  the  potato  and  the  Lima  bean  mildews,  and  their 
investigation  was  again  taken  up  with  two  points  chiefly  in  view ; 
viz.,  1st,  to  obtain  a  perfectly  satisfactory  medium  for  their 
artificial  culture,  and  2d,  to  determine  if  they  possess  mycelia  of 
distinct  sexual  strains.  As  another  mildew,  Phytophthora 
Thalictri,  on  Thalictrum,  including  its  oospores,  was  found  here, 
some  attention  was  paid  to  this  in  the  hope  that  it  might  throw 
some  light  on  the  latter  problem.  In  fact,  we  have  had  for  con- 
sideration all  of  the  species  of  Phytophthora  that  are  known  to 
occur  in  the  United  States. 

Altogether  over  a  thousand  cultures  of  the  potato  and  Lima 
bean  mildews  have  been  made  on  various  media.  The  general 
results  are  given  under  the  following  accounts  of  the  fungi.  By 
far  the  most  satisfactory  medium,  however,  is  that  described 
under  Lima  bean  juice  agar.  With  this  medium  one  can  grow 
either  of  these  fungi,  but  especially  the  Lima  bean  mildew,  almost 
as  easily  as  any  saprophytic  fungus.  They  make  a  progressive 
growth  on  this  medium  which  often  covers  the  whole  surface. 
With  the  Lima  bean  mildew  this  growth  retains  its  vitality  for 
some  months,  so  that  cultures  are  readily  renewed  at  any  time. 
With  the  potato  mildew  the  mycelium  does  not  live  so  long;  so 
the  cultures  have  to  be  renewed  more  frequently,  every  three  or 
four  weeks,  and  more  care  is  needed  in  its  renewal. 


ARTIFICIAL    CULTURES    OF    PHYTOPHTHORA.  893 

As  regards  the  sexual  mycelia  theory,  we  have  worked  from 
two  points  of  attack.  Our  chief  efforts  have  been  with  the 
downy  mildew  of  the  Lima  bean,  to  lose  the  oospores.  We  have 
tried  to  accomplish  this  by  Petrie  dish  separation  cultures  of 
the  conidia,  and  by  the  use  of  very  miinute  fragments  of  the 
mycelium  from  the  edge  of  the  cultures.  We  have  not  succeeded 
in  a  single  instance  in  permaneiTtly  doing  away  with  the  oospores 
by  either  of  these  methods,  and  in  some  cases  we  have  tried  both 
on  the  culture  in  hand.  With  unfavorable  media  one  can  tem- 
porarily prevent  the  formation  of  oospores,  but  these  always 
readily  develop  when  the  transfer  is  made  to  a  medium  favorable 
for  their  growth.  With  the  potato  mildew,  we  have  tried  to 
produce  the  oospores  by  crossing  the  fungus  with  cultures  from 
different  sources.  While  we  have  had  the  fungus  from  only  a 
few  different  localities,  none  of  the  crosses  between  these  have 
given  any  indication  of  oospore  formation.  These  results  have 
thrown  very  considerable  doubt  upon  the  theory  of  sexual 
mycelia. 

With  the  discovery  of  the  oospores  in  both  P.  Phaseoli  and  P. 
Thalictri,  their  continued  absence  in  P.  infestans,  especially  when 
the  theory  of  sexual  mycelia  does  not  seem  to  throw  light  on  the 
subject,  becomes  a  matter  of  still  greater  interest.  In  our 
previous  report  (p.  323)  we  gave  some  of  the  theories  that  have 
been  advanced  to  explain  their  absence,  of  which  one  was  that 
this  species  had  lost  the  power  to  produce  such  bodies.  Both 
Jones  and  the  writer  have  found,  under  certain  conditions,  bodies 
in  the  cultures  that  possibly  may  indicate  imperfect  attempts  on 
the  part  of  the  fungus  to  produce  these  spores.  It  is  barely 
possible,  with  the  continued  renewal  of  the  potato  by  the  asexual 
method  of  propagating  it  by  the  tubers  that  the  fungus  has  like- 
wise been  continually  renewed  asexually  by  its  mycelium  in  these, 
and  that  both  (the  potato  its  seeds,  and  the  fungus  its  oospores) 
have  thus  lost,  at  least  largely,  the  power  to  reproduce  them- 
selves sexually.  In  this  case  one  would  probably  find  the 
oospores  only  where  the  fungus  developed  on  the  wild  species  of 
Solanum  in  its  native  habitat. 

Pliytophthora  Thalictri  Wilson  &  Davis. 

Distribution.  This  species  was  first  described  by  Wilson 
(Bull.   Torr.   Bot.   Club  34:   392.      1907)    from   specimens   col- 


894         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

lected  by  Davis  in  June,  1907,  on  Thalictrum  purpurascens,  in 
Kenosha  Co.,  Wisconsin.  Dr.  Davis  informs  the  writer  that  he 
has  since  collected  the  fungus  there  and  in  another  locality  in  the 
same  state.  On  October  2,  1908,  at  Centerville,  and  again  on 
October  10,  at  Westville,  the  writer  found  this  species  on 
Thalictrum  polygamum  in  Connecticut.  These  collections  are 
apparently  the  only  ones  that  have  yet  been  made,  but  from  its 
occurrence  in  both  Wisconsin  and  Connecticut  it  seems  very 
likely  that  careful  search  will  reveal  its  presence  in  at  least  the 
intervening  states. 

Life  history.  Davis  did  not  find  the  oospores,  so  Wilson 
described  only  the  conidial  stage.  The  mycelium  causes  black 
spots  on  the  leaves,  practically  like  those  of  P.  infestans  on  the 
potato  leaves.  The  conidiophores  are  produced  only  sparingly 
on  the  under  surface  of  the  leaves.  The  most  important  of  the 
minor  differences  which  Wilson  gives  as  distinguishing  this  mil- 
dew from  that  of  the  potato  are  the  shorter  and  more  slender 
conidiophores  (300-400x5-7^,  with"  one  or  two  branches),  and 
slighter  smaller  and  more  elongated  conidia  (20-27  x  1 3-1  7ju,). 
The  writer  found  the  conidiophores  varying  from  2^o-^ooix,  and 
with  one  to  three  branches,  each  bearing  one  to  three  conidial 
swellings. 

The  writer  was  fortunate  in  finding  a  few  of  the  oospores 
which  as  yet  had  not  been  described.  These  were  formed  only 
rarely  and  in  moderation  in  a  few  of  the  leaves  found  at  the  very 
end  of  the  season.  Their  presence  in  the  tissue  could  be  deter- 
mined only  upon  careful  search  with  a  microscope  after  boiling 
the  leaf  tissue  in  caustic  potash  and  mashing  it  apart.  Those 
seen  by  the  writer  did  not  differ  very  materially  from  the 
oospores  of  P.  Phaseoli,  so  that  we  may  expect  those  of  P. 
infestans,  when  found,  to  be  of  similar  character. 

The  oospores  were  not  in  all  cases  mature,  but  they  seemed  to 
have  an  oogonial  wall  somewhat  more  deeply  tinted  than  those 
of  P.  Phaseoli.  So  far  as  could  be  determined,  the  antheridia 
and  oogonia  were  developed  from  different  mycelial  threads. 
The  oogonia  are  chiefly  subspherical,  with  moderately  thin, 
reddish-brown  tinted  walls,  loosely  enveloping  the  oospore,  and 
25-33/^  in  diameter.  The  oospores  are  spherical,  hyaline  or 
slightly  yellowish  tinted,  with  medium  thick  and  smooth  wall 
(3-4/a)  and  vary  from  18.5  to  25^  in  diameter. 


ARTIFICIAL    CULTURES    OF   PHYTOPHTHORA.  895 

As  the  Thalictrum  does  not  have  any  thickened  tissues  within 
which  the  myceHum  penetrates,  having  so  far  been  found  only 
in  the  leaves,  it  was  impossible  to  obtain  artificial  cultures  of 
this  fungus  after  the  manner  employed  with  the  other  two 
species. 

Infection  experiments.  Since  P.  Thalictri  resembles  P. 
infestans  so  closely,  the  writer  has  thought  that  possibly  they 
might  not  be  distinct  species.  Worthington  G.  Smith  (Diseases 
of  Field  and  Garden  Crops,  p.  275-6)  gives  a  list  of  different 
hosts  of  P.  infestans  which  include  even  two  Scrophulariaceae. 
Our  specimens  were  found  only  at  the  end  of  a  very  dry  season, 
and  were  not  in  very  good  shape  for  inoculation  tests.  At  that 
time  there  were  no  living  plants  of  potato  available  for  experi- 
mentation. Tests  of  the  spores  on  the  cut  surface  of  a  potato 
and  on  leaves  of  a  young  greenhouse  tomato  failed  to  give  any 
results.  Some  of  the  infected  specimens  of  Thalictrum  were 
taken  up  and  placed  in  a  moist  atmosphere  in  the  greenhouse, 
but  the  disease  did  not  develop  much  further.  The  past  spring, 
on  some  of  the  check  plants  of  Thalictrum,  developed  pre- 
maturely in  the  greenhouse,  the  writer  failed  to  produce  infec- 
tion with  spores  from  artificial  cultures  of  P.  infestans,  though 
these  succeeded  on  the  potato.  While  these  experiments  were 
perhaps  not  extended  enough  to  speak  positively,  still  they  at 
least  indicate  that  these  fungi  are  distinct  strains,  if  not  distinct 
species. 

Phytophthora  infestans  (Mont.)  DeBy. 

Life  history.  This  phase  of  the  subject,  especially  with  refer- 
ence to  the  conidial  stage,  has  been  so  thoroughly  presented  by 
DeBary  and  others  that  we  will  not  enter  particularly  upon  it 
here.  Some  idea  of  the  character  of  the  conidial  stage  may  be 
obtained  from  the  photomicrographs  shown  in  Plate  LXXI.  In 
our  former  article  (p.  304)  we  made  some  observations  upon 
the  manner  of  primary  infection  in  potato  fields,  which  were 
somewhat  different  from  the  views  formerly  held.  Such  obser- 
vations as  we  have  been  able  to  make  since  are  still  in  favor  of 
this  view.  If  it  could  be  proven  that  oospores  develop  in  the 
decaying  seed-tubers,  this  would  further  strengthen  it.  But  so 
far  we  have  never  been  able  to  positively  identify  oospores  in 
the  tubers  under  any  conditions,  though  one  often  runs  across 

63 


896         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

suspicious  looking  bodies  in  some  of  the  tubers  in  the  last  stages 
of  their  dry  decay. 

Upon  its  host  in  nature  this  fungus  confines  its  mycelium 
largely  to  the  intercellular  spaces  of  the  tissues.  This  necessi- 
tates special  branches,  or  haustoria,  for  penetration  into  the  cells 
for  the  food  supply.  The  haustoria  are  lacking  in  the  artificial 
cultures  on  agar  medium.  The  mycelium  in  cultures  on  living 
potato  plugs,  while  invading  superficial  tissues  and  cells,  does  not 
penetrate  very  deeply  or  set  up  a  special  decay.  This  certainly 
suggests  that  in  nature  much  of  the  soft  rot  following  attack  of 
the  tubers  is  due  to  bacterial  action.  Often  this  latter  becomes 
so  bad  as  to  crowd  out  the  original  invader.  The  haustoria 
often  seem  to  develop  further  in  storage  tubers,  or  at  least  their 
walls  become  thickened.  This  thickening  possibly  may  be  due  to 
an  envelope  of  the  plant  cellulose.  When  one  sees  two  of  these 
knobbed,  thickened  haustoria  within  a  cell  bending  towards  each 
other  as  if  about  to  conjugate,  the  impression  is  gained  that  this 
may  be  the  first  step  toward  the  formation  of  oospores.  But, 
though  we  have  examined  these  haustoria  carefully,  even  after 
the  infected  tubers  were  planted,  we  have  never  seen  any  further 
development  along  this  line. 

Smith  (loc.  cit.  p.  295)  claimed  to  have  discovered  the  oospores 
of  the  potato  fungus.  We  have  tried  to  obtain  specimens  of 
these  from  him  and  others,  but  have  not  succeeded.  Smith  wrote 
us  in  1906:  "No  doubt  you  know  that  the  oospores  became  a 
kind  of  political  subject — oospores  of  P.  infestans  or  not  oospores 
of  P.  infestans? ;  and  I  had  no  wish  to  go  on.  Botanists  and 
popular  writers  followed  what  they  took  to  be  the  safer  authority, 
just  as  Saccardo  has  done;  this  is  right  enough  in  a  way." 
Massee  thinks  that  Smith's  oospores  were  the  chlamydospores  of 
a  Fusarium,  as  he  writes  me :  'T  have  very  carefully  examined 
W.  G.  Smith's  type  slide  preparation,  and  am  positively  certain 
that  the  so-called  oospores  are  nothing  more  that  the  globose, 
thick-walled  chlamydospores  belonging  to  a  Fusarium."  From  a 
study  of  Smith's  drawings  and  an  experience  with  the  flora  and 
fauna  of  decaying  potatoes  the  writer  is  led  to  the  conclusion 
that  he  did  not  find  the  oospores  of  P.  infestans;  or  that,  if  he 
did,  he  also  got  other  things  mixed  up  with  them.  Our  studies 
with  the  oospores  of  F.  Phase oli  and  P.  Thalictri  would  also 
indicate  that  those  described  by  him  for  P.  infestans  were  too 


ARTIFICIAL    CULTURES   OF    PHYTOPHTHORA.  897 

different  to  be  such.  Since  his  time  others,  as  Smorawski,  have 
described  what  they  called  immature  oospores,  but  the  general 
belief  to-day  is  that  these  bodies  have  not  been  found. 

Our  culture  work  has  thrown  very  little  light  on  this  subject. 
In  some  few  of  the  earlier  cultures  we  found  occasional  bodies 
that  looked  something  like  an  attempt  at  oospore  formation. 
Jones  recently  (loc.  cit.)  has  further  studied  these  bodies,  and 
has  succeeded  in  producing  them  in  considerable  numbers  in  a 
special  potato  juice  gelatine  medium.  Our  impression  of  those 
seen  in  our  own  cultures  has  been  that  they  might  be  unusual 
mycelial  branches  produced  under  unfavorable  conditions  (pres- 
ence of  certain  bacteria,  etc.)  ;  and  from  what  we  have  seen  of 
Jones'  cultures  and  slides,  they  resemble  chlamydospores  as  much 
as  oogonia.  In  our  experience  with  the  oospores  of  P.  Phaseoli 
the  oogonia  were  developed  after  rather  than  before  the  anther- 
idia,  and  in  Jones'  cultures  we  saw  no  signs  of  antheridia.  It  is 
possible,  however,  if  there  really  are  sexual  mycelia,  that  this 
was  an  attempt  of  the  female  strain  to  produce  the  oogonia;  or, 
on  the  other  hand,  if  this  species  has  lost  the  power  of  producing 
oospores,  such  cultures  might  indicate  strains  in  which  this 
process  had  not  entirely  disappeared. 

Cultural  methods.  In  our  previous  report  we  described  the 
method  by  which  cultures  are  obtained  from  the  mycelium  of 
infected  tubers  by  taking  out  this  tissue  by  aseptic  methods  and 
inserting  it  on  cultural  media.  The  chief  precautions  which  have 
to  be  observed  are  the  use  of  tubers  in  which  the  infection  is  in 
its  first  stages  and  so  has  merely  tinted  the  superficial  tissue 
reddish-brown  without  any  soft  rot ;  also  the  sterilized  knife  used 
to  take  out  the  infected  tissues  should  be  allowed  to  cool  so  that 
the  cut  surface  is  not  seared.  It  is  best  not  to  have  liquid  in  the 
bottom  of  the  agar  culture,  or  if  so,  to  insert  the  tissue  above 
this,  as  the  water  may  spread  bacteria  that  may  be  included,  and 
so  spoil  the  culture.  Out  of  such  cultures,  at  least  some  with 
pure  growths,  or  growths  that  permit  of  pure  transfers,  can  be 
obtained. 

The  potato  mildew  forms  its  growth  more  in  the  air  and  less 
embedded  in  the  medium  than  the  Lima  bean  mildew.  Likewise 
the  mycelium  loses  its  contents  quicker,  and  so  renewal  from  old 
cultures  is  often  unsuccessful.  A  series  of  cultures  on  Lima 
bean  juice  agar,  varying  from  44  to  64  days  old,  failed  to  grow; 


898         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

others,  from  21  to  34  days  old,  grew  readily,  and  even  in  one  case 
a  culture  54  days  old  grew.  It  is  best,  however,  to  renew  the 
cultures  on  this  medium  at  least  once  every  month.  The 
mycelium  in  the  air  easily  collapses,  so  that  care  has  to  be  taken 
in  making  transfers;  especially  should  the  needle  be  completely 
cooled  ofif  before  inserting.  Both  aerial  and  embedded  material 
should  be  taken,  preferably  with  a  sharpened  platinum  wire,  in 
these  transfers. 

Media.  Of  all  the  media  tried  the  Lima  bean  juice  agar  gave 
by  far  the  best  results.  The  fungus  on  this,  if  properly  started, 
formed  a  luxuriant  growth  in  the  air  (see  Plate  LXX  a)  and 
usually  a  progressive  growth,  covering  the  surface  of  the  agar. 
This  medium  likewise  proved  best  for  the  Lima  bean  mildew, 
and  as  that  mildew  formed  oospores  unusually  abundantly  in  it, 
it  was  thought  that  the  potato  mildew  might  make  some  effort  in 
this  direction,  but  there  was  no  more  indication  of  these  bodies 
in  this  medium  than  in  those  in  which  the  potato  mildew  grew 
poorly.  The  following  notes  give  the  result  with  the  potato 
mildew  on  the  various  media  tried. 

Lima  bean  juice  agar  (504-10  +  500).  While  the  fungus  grew 
readily  on  both  the  weak  Lima  and  white  bean  agars  (made  from 
sliced  beans  and  so  not  as  nutritious  as  when  ground),  on  the  whole, 
the  strong  Lima  bean  agar,  as  given  below,  was  the  most  satis- 
factory. It  makes  on  this  a  luxuriant  aerial  growth  of  mycelium 
and  conidiophores,  that  tends  to  cover  the  surface  eventually. 
Conidia  were  produced  in  abundance,  but  no  oospores  or  peculiar 
swollen  mycelial  branches.  One  or  two  drops  of  lactic  acid  added 
to  it  usuallv  prevented  the  development  of  the  fungus.  See  illus- 
tration in  Plate  LXX  b  A-B. 

As  this  medium  has  proved  by  far  the  most  satisfactory  for  this 
mildew  and  that  of  the  Lima  bean,  as  well  as  for  certain  other 
fungi,  we  give  our  method  of  making  it.  We  used  a  50 -j-  10 -|-  500 
formula;  that  is,  50  grms.  of  dried  ground  Lima  beans,  10  grms. 
of  agar-agar  and  500  cc.  of  water.  The  beans  are  ground, as  fine 
as  possible  with  a  fruit  grinder,  and  then  50  grms.  soaked  one-half 
hour  in  tepid  water  (use  as  much  water  as  necessary,  but  of  course 
not  to  exceed  500  cc.  finally)  and  then  simmered  slightly  for 
another  half-hour.  Strain  off  liquid  through  fine  wire  strainer,  add 
agar-agar  (better  dissolved  in  small  amount  of  water)  and  water 
necessary  to  make  500  cc.  of  medium ;  heat  long  enough  to  thor- 
oughly mix  agar-agar  and  strain  again  through  wire  and  fine  cheese 
cloth  into  test  tubes. 

Corn  meal  juice  agar  (50-I- 10  + 500).  This  proved  a  far  more 
satisfactory  medium,  as  regards  aerial  growth,  for  this  than  for  the 
Lima  bean  mildew.  In  general,  it  gave  results  about  like  those 
with  potato  juice  agar;  that  is,  a  pure  white,  aerial  growth  around 
place  of  inoculation,  but  not  generally  progressive.  There  were  no 
oospores,  peculiar  chlam'ydospore-like  bodies,  or  unusual  swellings 
of  the  mycelium.     See  Plate  LXX  b  C. 


ARTIFICIAL    CULTURES    OF   PHYTOPHTHORA.  899 

Potato  juice  agar  (150*  +  10  + 500).  This  gives  a  localized  but 
evident  aerial  growth,  one-half  to  one  inch  in  diameter  around 
inoculation.  Similar  growths  on  pumpkin  juice  agar  (see  Plate 
XXV  c,  Report  1905)  were  obtained  in  1905.  Mycelium  same  as 
with  corn  meal  agar.     See  Plate  LXX  b  D. 

Lima  bean  phaseolin  agar ;  Nucleic  acid  peptone  sugar  agar ; 
Phaseolin  Pot.  Phos.  agar;  sugar  peptone  water  (see  Lima  bean 
mildew  cultures)  all  proved  unsatisfactory,  as  little  or  no  growth 
resulted. 

Lima  bean  juice  gelatin  (S0-|- 50+ 5oo).  Not  extensively  tried, 
but  apparently  about  the  same,  or  a  little  better,  than  next. 

Potato  juice  gelatin  (150 -}- 50 -|- 500).  Very  poor  medium, 
especially  for  aerial  growth.  In  specially  prepared  potato  juice 
gelatin  in  stab  cultures,  Jones  succeeded  with  certain  strains  in 
getting  the  peculiar  chlamydospore-like  bodies  (or  immature 
oogonia?)  spoken  of  earlier.  In  our  cultures  these  did  not  appear 
as  with  him,  though  certain  branches  did  produce  unusual  swellings 
that  had  a  bacterial-like  deposit  around  them. 

Living  plugs  of  potato,  etc.  As  reported  in  1905,  living  plugs  of 
potato  and  of  pumpkin,  especially  the  former,  offer  a  good  medium 
for  a  (usually  sparse)  conidial  growth  of  the  fungus.  These  plugs 
should  be  on  moist  cotton.  The  growth  does  not  cause  any  soft 
decay,  though  the  superficial  tissues  often  turn  reddish-brown.  The 
mycelium  does  not  penetrate  very  deepl}-,  but  sometimes  invades  the 
cells.  The  haustoria  are  not  formed  so  frequently  as  in  nature. 
Jones  found  considerable  difference  in  the  growth  on  different 
varieties.  This  probably  affords  a  means  for  testing  resistance  of 
varieties,  but  I  am  under  the  impression  that  those  showing  most 
resistance  will  prove  to  be  undesirable  varieties,  as  the  less  starchy, 
soggy  ones.     (See  1905  Report,  Plate  XXV  a.) 

Corn  meal  (moisten  with  water  or  potato  juice).  In  my  1905 
tests  this  proved  the  most  satisfactory  medium  used,  as  when 
started  it  favored  a  luxuriant,  progressive  growth.  The  objection  to 
it  is  that  the  corn  meal  dries  out  so  that  it  is  difficult  to  get  cultures 
started,  and  the  medium  interferes  somewhat  with  microscopic 
examination.     (See  1905  Report,  Plate  XXV b.) 

Cross  cultures.  In  order  to  test  the  mycelial  sexual  strain 
theory,  the  writer  has  from  time  to  time  inoculated  the  above 
media  with  this  mildew  from  different  sources.  The  Lima  bean 
juice  agar  affords  by  far  the  best  one  for  such  tests,  as  it  allows 
progressive  growths.  The  usual  method  has  been  to  inoculate 
the  bottom  of  the  tube  with  a  culture  from  one  source  and  above 
this — one-half  to  one  inch — with  a  culture  from  a  second  source. 
With  the  Petrie  dish  (see  Plate  LXX  a)  three  or  four  inocula- 
tions can  be  made  if  extreme  care  is  used  against  contamination. 
Such  cross  inoculations  have  been  made  with  cultures  obtained 
from  tubers  from  several  sources  in  Connecticut,  and  one  each 
from  Maine,  Long  Island,  Vermont  and  Holland,  the  writer 
being  indebted  to  Jones  for  cultures  from  the  last  two  sources. 


*Took  150  grms.  peeled  potato,  thinly  sliced,  soaked  in  tepid  water,  and 
then  simmered  for  half-hour,  and  used  juice  from  this. 


900         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

While  these  cultures  have  not  been  extended  enough,  perhaps, 
to  speak  positively,  yet  in  none  of  them  was  there  any  indication 
of  an  unusual  mycelial  development  or  of  the  formation  of 
oospores.  We  have  noticed  some  difference  in  the  vigor  of  these 
growths,  as  Plate  LXX  a  shows,  but  this  may  be  due  to  more 
material  used  in  one  inoculation  than  in  another,  or  to  the  age  of 
the  cultures  used,  as  a  culture  not  frequently  renewed  tends  to 
run  out. 

Hybrid?  cultures.  Blakeslee  found  that  when  certain  distinct 
species  of  Mucoraceae  were  crossed  with  opposite  strains  there 
was  an  effort  to  form  the  sexual  spores.  As  the  Lima  bean  mil- 
dew cultures  possessed  both  of  these  strains,  if  they  exist,  it  was 
thought  that  cultures  containing  both  P.  infestans  and  P.  Phaseoli 
might  induce  the  former  to  make  an  attempt  at  oospore  forma- 
tion. Certain  tubes,  therefore,  were  inoculated  with  the  Lima 
bean  mildew  below  and  the  potato  mildew  above.  Petrie  dishes 
were  also  inoculated  with  the  Lima  bean  mildew  in  the  center  and 
the  potato  mildew  from  several  sources  around  this.  Of  course 
one  would  expect  the  Lima  bean  mildew  to  produce  its  oospores 
within  the  area  covered  by  its  own  mycelium,  but  at  the  juncture 
of  the  area  covered  by  the  potato  mildew  one  might  look  for 
attempted  hybrid  oospores  if  the  same  condition  prevailed  as  with 
the  mucors. 

At  first  the  writer  was  inclined  to  believe  that  such  hybrid 
oospores  did  result.  At  the  juncture  of  the  cultures  and  within 
the  area  occupied  by  P.  infestans  occurred  certain  immature 
oogonia  that  were  larger,  somewhat  thicker- walled,  and  of  a 
darker  reddish-brown  tint  than  those  produced  by  P.  Phaseoli 
under  ordinary  conditions.  One  of  these  doubtful  hybrid 
oogonia  is  shown  in  Plate  LXXIV  B.  In  all  of  these  cultures 
there  appeared  in  time  mature  oospores,  more  or  less  abundant, 
around,  in  and  under  the  P.  infestans  colonies,  but  these  were  not 
different  from  the  oospores  of  P.  Phaseoli.  Moreover,  the 
renewal  cultures  made  from  the  edge  of  the  P.  infestans  colonies 
on  the  opposite  side  of  the  tube  from  the  P.  Phaseoli  colony 
always  gave  what  seemed  to  be  pure  growths  of  P.  Phaseoli. 
These  results  apparently  mean  that  the  Lima  bean  mildew 
mycelium  being  more  aggressive,  penetrated  into  the  potato 
mildew  colony  and,  forming  its  oospores  under  somewhat 
unfavorable  conditions  (due  to  toxins  in  the  medium  produced  by 


ARTIFICIAL    CULTURES   OF   PHYTOPHTHORA.  90 1 

the  growth  of  the  former  mildew),  certain  of  these  had  been 
arrested  or  otherwise  affected  in  their  development,  as  sometimes 
occurs  in  unfavorable  media.  The  potato  mildew  mycelium, 
being  shorter  lived,  was  entirely  crowded  out  by  the  more 
aggressive  Lima  bean  mildew  when  the  renewals  were  made. 

Phytophthora  Phaseoli  Thaxt. 

Life  history.  In  our  previous  report  we  gave  rather  complete 
details  concerning  the  life  history  of  this  fungus.  The  general 
character  of  the  mycelium,  the  conidia,  and  the  conidiophores  is 
shown  by  the  photomicrographs  of  Plate  LXXIII.  Such  infor- 
mation as  has  been  gained  during  the  present  investigation  has 
been  chiefly  concerning  details  in  the  development  of  the  sexual 
spores.  Due  to  improvement  in  cultural  methods,  we  have  been 
able  to  produce  the  oospores  in  great  abundance  in  artificial 
cultures  (see  Plate  LXXIVA).  Usually  it  takes  from  six  to 
ten  days  after  the  start  of  the  culture  before  there  are  any  very 
evident  signs  of  these  bodies,  but  with  a  favorable  medium,  such 
as  strong  Lima  bean  agar,  they  then  develop  very  rapidly,  so 
that  practically  full-grown  oospores  can  be  found  in  ten  to  fifteen 
days.  If  the  culture  gives  a  progressive  growth,  different  stages 
may  be  found  starting  from  the  edge  inward,  the  outermost 
growth,  of  course,  being  free  from  them.  While  the  Lima  bean 
juice  agar  gives  by  far  the  greatest  development  of  oospores,  it 
is  not  quite  so  favorable  for  their  study,  because  of  the  usually 
abundant  aerial  growth,  as  corn  meal  juice  agar.  This  latter 
medium  gives  a  very  scanty  growth,  there  being  practically  no 
aerial  development.  The  embedded  threads  are  largely  con- 
cerned in  producing  the  oospores,  which  are  very  slowly 
developed,  and  in  old  cultures  show  all  stages,  most  of  them  never  - 
reaching  maturity. 

The  first  step  toward  sexual  reproduction  seems  to  be  the  large, 
irregular  swellings  that  develop  in  certain  of  the  threads  (see 
Plate  LXXIVC).  We  have  not  been  able  to  determine  any 
fusion  of  the  mycelial  branches  that  proceeds  or  accompanies 
these  swellings,  but  often  they  are  more  or  less  massed.  Very 
frequently  a  terminal  swelling  develops  a  normal  thread  much 
like  a  germ-thread,  into  which  the  contents  pass,  and  this  may 
give  rise  to  subsequent  swellings.     Such  empty  swellings  in  size 


902         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

and  shape  are  often  quite  similar  to  the  antheridia,  and  perhaps 
may  be  tentative  antheridia  that  fail  of  full  development  because 
of  lack  of  contact  with  tentative  oogonial  branches. 

It  is  impossible  in  the  majority  of  cases  to  determine  whether 
the  antheridium  and  the  oogonium  come  from  the  same  or  from 
different  mycelial  branches.  In  quite  a  number  of  instances, 
however,  we  have  been  able  to  satisfy  ourself  that  they  originated 
on  distinct  branches  (see  Plate  LXXIV  J,  K)  and  in  some  cases 
have  traced  these  as  independent  for  some  distance.  Of  course 
such  branches  might  originate  finally  from  the  same  mycelium, 
but  inasmuch  as  they  remain  independent  as  far  as  they  can  be 
traced,  they  admit  of  the  possibility  of  distinct  sexual  mycelia. 
However,  in  a  few  cases  (see  Plate  LXXIV  H,  I)  we  have  seen 
them  where  they  seemed  to  come  from  the  same  thread.  Our 
results,  in  failing  to  permanently  lose  the  oospores,  would  also 
indicate  their  final  common  origin. 

In  the  development  of  the  sexual  stage,  the  antheridium  is  the 
first  to  appear,  and  is  often  apparently  fully  developed  before 
there  is  much  evidence  of  the  oog'onium  (see  Plates  LXXIV  E 
and  LXXVA).  Whether  or  not  the  peculiar  swellings  spoken 
of  earlier  develop  into  antheridia  as  a  result  of  contact  with 
certain  other  threads  or  swellings,  it  is  difficult  to  determine,  but 
it  seems  most  probable  (Plate  LXXIV  D).  This  potential 
oogonial  thread,  with  or  without  a  swelling,  becomes  attached 
to  the  base  of  the  antheridium  and  grows  up  along  its  surface 
toward  the  apex.  Very  often  it  can  be  seen  when  it  has  only 
partially  covered  the  length  of  the  antheridium,  as  shown  in 
Plate  LXXV  B.  For  a  long  time  it  was  difficult  to  decide 
whether  or  not  these  threads  did  not  actually  penetrate  the 
antheridium  and  grow  through  it,  and  we  are  not  yet  certain  that 
this  does'  not  sometimes  occur.  Certainly  the  optical  effect  is 
frequently  that  of  an  internal  thread  with  its  apical  wall  very 
thin  as  compared  with  the  side  walls,  as  shown  in  Plate  LXXV  A, 
B.  In  time,  however,  the  oogonial  thread  reaches  the  top  of  the 
antheridium,  and  curving  around  its  apex,  begins  to  swell  into 
the  oogonium  (Plates  LXXIV  E  and  LXXVC),  which  by  this 
time  is  usually  cut  off  from  its  basal  thread  by  a  septum.  The 
various  stages  of  its  enlargement  are  shown  in  Plate  LXXIV  F, 
G,  H.  After  the  full  size  is  reached  the  contents  begin  to  be 
differentiated,  marking  off  the  oosphere   (Plate  LXXIV  G,  H)'. 


ARTIFICIAL    CULTURES   OF    PHYTOPHTHORA.  903 

About  this  time  fertilization  by  the  antheridium  usually  takes 
place,  but  whether  by  means  of  a  penetration  tube  or  merely  by 
a  local  opening  where  the  walls  of  the  two  bodies  are  in  contact, 
was  not  made  out.  If  the  oogonial  thread  really  ever  penetrates 
the  antheridium,  a  union  of  certain  of  their  protoplasmic  contents 
no  doubt  takes  place  at  that  time. 

After  the  demarcation  of  the  oosphere  by  the  thin  wall,  the 
subsequent  evident  change  is  in  the  gradual  thickening  of  this 
wall  until  there  is  formed  the  fully  developed  oospore  loosely 
enveloped  by  the  oogonial  sac  (Plate  LXXIVI-K).  These 
oospores  in  cultures  vary  considerably  in  size  (Plate 
LXXVD-G),  and  often  there  are  a  good  many  that  never  reach 
maturity.  They  are  hyaline  or  slightly  yellowish  tinted.  We 
have  made  no  study  of  the  cytological  phenomena  that  accompany 
their  formation,  but  the  profusion  with  which  they  are  developed 
in  cultures  should  readily  permit  such  study.  We  have  not  yet 
succeeded  in  germinating  such  spores,  as  they  apparently  require 
at  least  a  winter's  rest  before  this  takes  place. 

Cultural  methods.  The  Lima  bean  mildew  may  be  obtained  in 
cultures  by  care  in  selecting  beans  from  pods  recently  attacked. 
It  is  usually  best  to  use  pods  showing  a  fresh  and  comparatively 
slight  growth  that  has  barely  penetrated  into  the  interior,  using 
the  beans  beneath  that  show  little  or  no  sign  of  attack  to  the 
naked  eye.  Such  beans,  if  transferred  by  aseptic  means  to  test 
tubes  containing  moist  cotton,  will  in  time  give  an  aerial  growth 
that  is  frequently  uncontaminated  by  other  fungi  or  even  by 
bacteria.  From  these  pure  cultures  on  Lima  bean  juice  agar 
can  be  secured. 

In  my  previous  work,  the  cultures  finally  ran  out,  after  two 
or  three  months.  This  was  because  of  contamination,  and  the 
use  of  poor  media  for  growth.  In  my  recent  work,  by  getting 
pure  cultures  to  start  with,  and  the  use  of  a  favorable  medium 
for  growth,  I  have  had  no  trouble  of  this  kind.  In  fact,  the 
mildew  grows  as  readily  (perhaps  a  little  more  slowly)  as  most 
saprophytic  forms,  and  is  easily  renewed  by  transfers.  In  these 
renewals,  the  needle  should  be  cooled  after  flaming,  and  then  a 
quantity  of  the  mycelium  and  agar  should  be  dug  out  and 
embedded  in  the  base  of  the  new  tube.  By  such  means  cultures 
have  been  kept  growing  for  over  seven  months  and  there  seems 
to  be  no  reason  why  they  cannot  be  continued  indefinitely. 


904        CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

The  mycelium  of  the  Lima  bean  mildew  lives  in  these  cultures 
much  longer  than  that  of  the  potato  mildew,  probably  because  of 
a  more  embedded  growth  in  the  agar,  due  to  the  formation  of 
oospores,  and  so  the  cultures  are  renewed  much  easier,  and  can 
be  left  without  renewal  for  a  longer  time.  A  series  of  trials  was 
made  to  determine  how  old  a  culture  on  Lima  bean  juice  agar 
could  be,  and  still  retain  its  vitality.  In  the  first  test,  ten  cultures, 
varying  from  28  to  43  days  old,  were  used.  These  all  grew 
readily.  Renewals  from  the  same  cultures  were  made  when  they 
varied  from  49  to  64  days  old,  again  from  these,  when  65  to  95 
days  old,  and  still  again,  when  92  to  136  days  old;  and  every  one, 
except  two  spoiled  by  bacteria,  made  fine  vigorous  growth,  with 
oospores  in  abundance.  Renewals  from  cultures  older  than  136 
days  have  not  been  tried,  but  presumably  would  be  successful. 
As  the  oospores  did  not  germinate,  the  renewed  growth  was  made 
from  the  mycelium,  since  the  conidia  were  probably  too  old  for 
germination  in  most  cases. 

Media.  As  with  the  potato  mildew,  the  strong  Lima  bean 
juice  agar  forms  by  far  the  best  medium  for  the  growth  of  the 
Lima  bean  mildew.  Not  only  did  the  conidial  stage  develop  a 
more  or  less  luxuriant  aerial  growth,  but  oospores  were  formed 
usually  in  great  luxuriance  (see  Plate  LXXIV  A),  at  the  surface 
and  slightly  embedded  in  the  agar.  Usually  there  is  no  indica- 
tion to  the  naked  eye  whether  or  not  oospores  are  produced  in 
the  cultures,  but  in  this  medium  with  certain  old  cultures,  after 
the  aerial  growth  had  collapsed  or  when  formed  less  abundantly 
than  usual,  their  presence  in  great  abundance  could  be  told  by 
two  or  three  reddish-brown  bands  showing  somewhat  faintly 
toward  the  outer,  thinner  part  of  the  culture.  These  darker 
bands  contained  more  oospores  than  the  intervening  lighter  ones. 
In  general,  the  oospores  were  produced  more  abundantly  in  the 
more  nutritious  media;  also  the  presence  of  acid  limited  or 
prevented  their  formation.  The  details  of  the  growth  of  the 
fungus  in  different  media  is  given  in  the  following  notes. 

Lima  bean  juice  agar  (50 -f- lo-j- 500).  While  on  this  medium 
(Plate  LXXIIbB,  C)  the  mildew  formed  a  more  or  less  vigorous 
aerial  growth  of  mycelium  and  conidiospores,  it  was  never  quite  so 
luxuriant  as  was  the  potato  mildew.  Oospores  were  always 
developed  in  abundance  in  the  strong  Lima  bean  agar,  but  were  not 
so  numerous  in  the  weak  Lima  or  white  bean  agar.  A  progressive 
growth  of  the  fungus  nearly  always  occurred  on  these  media,  often 
covering  the  surface.    With  the  strong  Lima  bean  agar,  even  when 


ARTIFICIAL    CULTURES   OF    PHYTOPHTHORA.  905 

it  was  apparently  made  up  under  about  the  same  conditions,  there 
was  noticed  considerable  difference  in  the  growth  of  the  fungus  on 
it.  This  was  probably  due  to  slight  variations  in  the  medium 
(differences  in  cooking,  sterilizing,  etc.)  rather  than  to  the  fungus, 
as  it  showed  most  strongly  in  sets  of  tubes  made  at  different  times. 
This  variation  showed  in  greater  or  less  luxuriance  of  aerial 
growth,  and  in  greater  or  less  luxuriance  of  oospore  production, 
and  especially  in  the  banded  appearance  already  spoken  of.  This 
latter  usually  occurred  where  less  luxuriant  aerial  but  progressive 
embedded  growth  took  place  above  the  base  of  the  tube.  A  cul- 
tural medium  made  from  fresh  green  Lima  beans  did  not  prove  any 
more  satisfactory  than  from  the  dried  beans.  The  addition  of  one- 
half  gram  nucleic  acid  to  weak  Lima  bean  agar  affected  the  growth 
somewhat  unfavorably,  often  limiting  it  to  a  dense,  white  aerial 
development  around  the  inoculation  material.  This  was  largely 
mycelium,  as  few  conidia  or  conidiophores  were  formed,  and 
oospore  formation  was  almost,  if  not  altogether,  prohibited.  One 
or  two  drops  of  lactic  acid  usually  prevented  any  growth  whatever. 
Powdered  willow  charcoal  (one  teaspoonful  to  500  cc.  of  the 
medium)  made  a  black  background  in  striking  contrast  to  the 
white  aerial  growth,  but  did  not  seem  to  affect  particularly  the 
development  of  the  fungus.  Cultures  of  the  fungus  grown  on 
white  bean  juice  agar  failed  to  infect  young  white  beans  (always 
exempt  in  nature),  though  the  young  Lima  beans  inoculated  at  the 
same  time  were  killed. 

Corn  meal  juice  agar  (5o-|-io4- Soo).  This  gave  practically  no 
aerial  growth,  and  but  a  slight  embedded  growth,  that  spread  slowly 
for  a  short  distance  from  the  point  of  inoculation.  The  production 
of  oospores  took  place,  and  because  these  showed  in  all  stages 
(many  failing  entirely  to  develop  further)  and  with  no  aerial 
growth  to  bother,  such  cultures  were  well  adapted  to  the  micro- 
scopical study  of  the  sexual  organs,  merely  by  mashing  small  pieces 
of  the  medium  under  a  cover  glass.     Plate  LXXII  b  E. 

Potato  juice  agar  (150 -|- 10+ 500).  The  growth  differed  quite 
markedly  from  that  of  potato  mildew  on  this  medium,  as  there  was 
no  aerial  development.  The  embedded  growth  was  more  evident 
than  on  the  corn  meal,  and  consisted  of  a  rather  matted  develop- 
ment of  mycelial  threads,  with  very  few  conidiophores  and  conidia. 
Practically  no  oogonia  were  formed,  and  the  few  attempted  did  not 
produce  oospores.  The  mycelium  did  not  form  irregular  swellings 
so  abundantly  as  usual,  and  so  was  more  like  that  of  P.  infestans. 
Plate  LXXII  b  D. 

Sugar  peptone  agar  (4-|- 2+ 10  + 5oo).  The  fungus  failed  to 
grow,  or  made  only  a  slight  growth  around  the  inserted  material, 
but  with  one-half  gram  of  nucleic  acid  added,  it  made  a  somewhat 
more  evident  growth  at  the  point  of  inoculation.  Very  few 
conidia  were  formed,  and  practically  no  mature  oogonia.  Phaseolin 
Pot.  Phos.  agar  (^ -1- i^ -f- 10 -(- 500)  cultures  practically  failed  to 
grow.     Sugar  peptone  water  (4  -|-  2  -j-  500)   failed  entirely  to  grow. 

Lima  bean  juice  gelatin  (50 -|- 50 -f  500).  This  is  3.  poor 
medium,  and  usually  only  a  slight  aerial  growth  of  mycelium  and 
conidiophores  with  conidia  takes  place  in  surface  cultures,  and  in 
stab  cultures  only  a  slight  development  of  mycelium,  with  no 
chlamydospore-like  bodies.  No  mature  oospores  occurred,  and 
there  were  few  attempts  to  start  these,  but  the  mycelium  had  more 
or  less  of  the  swellings.  The  walls  of  the  imperfect  oogonia  were 
thicker  and  more  strongly  tinted  than  usual. 

Potato  juice  gelatin  (1504- 50 -f  500).  Similar  to,  but  even 
poorer  than  the  preceding,  but  with  no  sign  of  oospore_  production 
and  mycelium  even  with  few  swellings.     Surface  of  medium  in  time 


god        CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

becomes  darkened  in  color,  due  to  oxidation,  and  the  conidia,  conidi- 
ophores  and  mycelium  take  on  this  tint  somewhat.  There  was 
no  development  of  the  peculiar  chlamydospore-like  bodies  found  by 
Jones  with  the  potato  mildew  in  his  special  preparation  of  this 
medium. 

Ground  Lima  beans  (with  just  water  enough  to  keep  moist  after 
sterilization).  Used  both  green  and  dried  beans,  and  also  green 
beans  with  the  pods  ground  with  them,  but  the  addition  of  the 
latter  proved  of  no  particular  value.  The  fungus  formed  a  rather 
luxuriant,  fluffy,  aerial  growth,  composed  of  mycelium  and  conidio- 
phores.  Some  oospores  formed  in  time  in  the  tissues.  On  the 
whole,  not  so  convenient  a  medium  for  study  as  the  agar  mediuni. 
Plate  LXXII  b  A. 

Living  Lima  beans.  These  were  taken  from  the  interior  of 
unbroken  pods  by  aseptic  means,  and  placed  in  sterilized  tubes  on 
moist  cotton,  and  then  were  inoculated.  Or  they  were  taken  already 
inoculated  from  the  infected  pods.  Sometimes  an  evident  aerial 
growth  of  mycelium  and  conidiophores  appeared  on  these,  and 
sometimes,  when  the  surface  was  unbroken,  no  external  growth 
showed,  though  the  seed  coats  were  discolored  by  a  reddish-brown 
dr}^  rot.  Oospores  were  formed  more  or  less  abundantly  within 
the  tissues. 

Corn  meal  (with  water  enough  to  keep  moist  after  sterilization). 
The  fungus  practically  failed  to  grow  in  this  medium.  With  our 
cultures  in  1905,  when  it  was  mixed  with  ground  Lima  beans  and 
pods,  etc.,  growths  were  obtained.  The  drying  out  of  this  medium 
in  itself  often  prevents  growth  starting,  and  corn  meal  certainl}'  is 
not  so  favorable  for  this  as  for  the  potato  mildew. 

Attempts  to  lose  oospores.  Our  cultures  of  this  fungus 
obtained  last  fall  were  from  seven  infected  beans  from  the 
Experiment  Station  grounds  and  a  market  garden  at  Westville. 
These  cultures  have  been  continued  distinct  ever  since.  Our 
idea  in  connection  with  the  sexual  strain  theory  had  been  that 
possibly  by  obtaining  cultures  of  the  fungus  early  in  the  season, 
certain  ones  might  be  run  across  in  which  oospore  production  did 
not  take  place  owing  to  the  presence  of  only  a  single  strain. 
Last  year  the  mildew  did  not  appear  on  the  Lima  bean  until  the 
very  end  of  the  season,  our  first  cultures  being  obtained  Sep- 
tember 29th.  The  cultures  from  these  seven  beans  all  produced 
oospores.  In  fact,  they  have  continued  to  do  so  ever  since, 
except  when  grown  under  unfavorable  conditions. 

It  being  settled  that  both  strains  were  present,  if  such  existed, 
the  next  attempts  were  to  get  rid  of  one  by  means  of  the  Petrie 
dish  separation  method  with  the  conidia.  It  was  found  by  Van 
Tiegham  cell  tests  with  nutrient  agar  medium  that  these  spores 
did  not  usually  germinate  very  readily,  and  when  they  did  it 
was  by  means  of  germ  tubes  that  did  not  make  a  very  extended 
growth.  However,  in  the  poured  Petrie  dishes  from  the  melted 
Lima  bean   agar  tubes,   having  the   introduced  mass  of   spore- 


ARTIFICIAL    CULTURES    OF    PHYTOPHTHORA.  907 

bearing  mycelium  shaken  through  them,  it  was  found  that  usually 
numerous  more  or  less  isolated  growths  started  up  (see  Plate 
LXXII  a).  These  usually  were  so  closely  situated  that  they  ran 
together,  so  that  distinctly  isolated  colonies,  presumably  from  a 
single  spore,  did  not  often  occur  after  the  first  few  days  of 
growth.  That  these  growths,  at  least  sometimes,  came  from  the 
germinating  conidia  rather  than  fragments  of  the  mycelium,  was 
shown  on  microscopic  examination  of  the  very  young  colonies. 
From  the  most  isolated  of  these  growths,  and  as  early  as  possible, 
transfers  were  made  to  individual  tubes.  Petrie  dish  separation 
cultures  were  even  made  from  these  a  second  and  a  third  time, 
but  always  with  the  result  that  the  oospores  eventually  appeared 
if  the  medium  used  was  a  favorable  one.  In  some  cases  where 
the  medium  was  unfavorable,  as  potato  juice  agar,  or  where  it 
was  made  acid,  these  oospores  largely  or  entirely  disappeared, 
but  they  always  came  back  as  abundantly  as  ever  when  transfers 
were  made  to  strong  Lima  bean  juice  agar.  These  results  are 
very  strongly  against  the  theory  of  distinct  mycelial  strains,  the 
chief  loophole  being  that  the  colonies  were  never  from  isolated 
spores,  which  seems  quite  improbable  from  the  numerous 
transfers  made  from  time  to  time. 

The  second  method  employed  to  get  rid  of  the  oospores  was 
by  means  of  transferring  single  isolated  threads  from  the  edge 
of  the  growth.  This  fungus  does  not  afford  a  very  good  oppor- 
tunity for  such  attempts.  However,  with  the  aid  of  a  magnifier, 
one  can  sometimes  get  very  small  fragments  from  the  mycelium 
that  shows  slightly  embedded  on  the  surface  of  the  agar.  Unless 
submerged  hidden  threads  extended  further  than  these  visible 
ones,  which  seems  improbable,  it  is  certain  that,  in  some  of  the 
numerous  trials,  fragments  of  a  single  thread  were  transferred. 
The  results  with  these,  however,  were  the  same  as  with  the  ordi- 
nary renewals,  namely,  an  abundance  of  oospores  on  the  Lima 
bean  juice  agar. 


PLATE  LX. 


Apple,  p.  853. 


a.     Showing  peridia  not  split  open.     X  2. 


Quince,  p.  851. 


Apple,  p.  853. 


?■  'W-'^'^^V*  '^'^^ 


b.     Peridia  split  open.     X  2. 


c.     Peridia  worn  away. 
RUSTS  OF  APPLE  AND  QUINCE. 


String  Bean,  p.  859. 


PLATE  LXI. 


Lima  Bean,  p.  859. 


a.     Chlorosis  (infectious  ?). 


b.     Clilorosis  (non-infectious). 


c.     Clilorosis  (infectious  ?)  of  Musk  Melon,  p.  865. 
CHLOROSIS  TROUBLES  OF   BEANS  AND   MUSK   MELON. 


PLATE  LXII. 


Chestnut,  p.  879. 


a.     Winter  injury  of  wood  ? 


b.     Diaporthe  canker. 


I         I 


c.     Powdery  Mildew  of  Grape,  p.  855.     X  2. 
DISEASES  OF  CHESTNUT  AND  GRAPE. 


PLATE  LXIII. 


a.     On  parsley  refuse,  p. 


b.     Artificial  cultures,  p. 


Check.  Inoculated. 

c.     Showing  drop  of  lettuce  leaves  two  days  after  inoculation,  p.  864. 


DROP   FUNGUS,  Sclerotinia  Libcrtiana,   OF   PARSLEY,   LETTUCE,   ETC. 


PLATE  LXIV. 


c.     Bacterial  Spot  of  Larkspur,  p.  862. 
DISEASES  OF    MAPLE,   LILY  AND   LARKSPUR. 


PLATE  LXV. 


a.     Showing  large  galls.     Reduced. 


b.     Showing  structure  of  small  galls.     Natural  size. 
LIMB  GALL  OF   OAK,  p.  866. 


PLATE  LXVI. 


a.     Powdery  Mildew  of  New  Jersey  Tea,  p.  866. 


b.     Calico  from  tobacco  on  tomato  and  then  back  to  tobacco,  p.  857. 
SOME   DISEASES  OF   NEW  JERSEY  TEA,  TOBACCO  AND  TOMATO. 


PLATE  LXVII. 


a.     Showing  manner  of  cutting  back,  spring  of  1906. 


b.     Showing  growth  made  by  fall  of  1908. 
PEACH   TREES  WINTER   INJURED  IN    1903-4,  p.  874. 


PLATE  LXVIII. 


a.     Gummosis,  following  winter  injury,  p.  869. 


b.     Collar  Girdle  with  c.     resulting  death  of  tree  ; 

due  to  winter  injury  in  1907-8,  p.  856. 

SOME    RESULTS  OF  WINTER   INJURY  TO   PEACH. 


PLATE  LXIX. 


a.     Bacterial  Spot,  showing  shot  hole  effect,  p.  856. 


b.     Last  stage  of  Yellows,  showing  adventitious  growths,  p.  872. 
SOME   DISEASES  OF  THE    PEACH. 


PLATE  LXX. 


a.     Petrie  dish  cross  cultures  from  three  sources,  p.  899. 


A      9      8       V     C 


b.     Growths  on  various  media,  p.  89S. 
ARTIFICIAL   CULTURES  OF    POTATO   MILDEW,  P/iyfop/it/iora  iiifcsfans 


PLATE  LXXI. 


a.  mycelium;     b.  conidiophores;     c.  conidia.      X  600  (about). 
DETAILS  OF    CON  I  DIAL  STAGE   OF   Phytophthora  hifcstaiis,  p.  895. 


PLATE  LXXII. 


a.     Petrie  dish  separation  culture,  p.  907. 


u 

b.     Growths  on  various  media,  p.  904. 
ARTIFICIAL   CULTURES  OF   LIMA  BEAN    MILDEW,  Phytophthonx  I'hascoli. 


PLATE  LXXIII. 


a.   mycelium;     a',   mycelial  swellings;    b.  conidiophores;    c.  conidia.     X6oo(about). 
DETAILS  OF   CONIDIAL   STAGE  OF  Phyfophthora  P/iascoli,  p.  901. 


PLATE  LXXIV. 


. 

'2 

H 

-c 

SI- 

-•  c 

<i-- 


a.   mycelium;      b._  potential  antheridia  ?  ;      c.  antheridia;      d.  anthcridial  tlireads; 

e.  oogonia;      f.  oogonial  threads;      g.  oosphere;      h.  oospores. 

X  600  (about)  except  A. 


DETAILS  OF   SEXUAL  STAGE  OF  Phytopiithora  Phascoli,  pp.  901-3. 


PLATE  LXXV. 


a.  antheridia;      b.  antheridial  threads;      c.  oogonia;      d.  oogonial  threads; 
e.  oospores.     X  1200  (about);  oil  immersion;     G.  stained. 

DETAILS  OF  ANTHERIDIA  AND  OOGONIA  OF  Pliyfophlliora  /Viasco/i,  pp.  902-3. 


INDEX. 


Page. 

Acetanilid 687 

headache  powders,  discussion  of  analyses  of  689 

Acetphenetidin    687 

headache  powders,  discussion  of  analyses  of 691 

Acetylene    798 

Acid  phosphate,  analyses  of  31,  483 

Agronomist,  report  of   397 

Agronomy,  extension  work  in  448 

Albulac    711 

Aleyrodes  vaporariorum   806,  815 

Alfalfa,  yellowing  of   850 

Allspice    IS4,  157 

Alsophila  pometaria   783,  795 

American  Agricultural  Chemical  Co. : — 

A.  A.  C.  Co.'s  Complete  manure  with  10%  potash  3,  62,  63,  455,  462 
Complete  tobacco  manure.,. 3,  104,  105,  455,  558,  559 
Grass  and  lawn  top  dressing.. 3,  96,  97,  455,  544,  545 

H.  G.  tobacco  manure 3,  10,  455,  462 

Southport  XX  special 3,  58,  59 

Superphosphate 3,  68,  69,  455,  520,  521 

Tobacco  starter  and  grower. .  .3,  88,  89,  100,  loi,  455, 

540,  541,  554,  555 

Dry  ground  fish 3,  44,  46,  47,  455,  498,  499 

Fine  ground  bone  3,  42,  43,  455,  494,  495 

Grass  and  oats  fertilizer 3,  98,  99,  455,  554,  555 

Acid  phosphate  3,  32,  33,  455,  462 

Castor  pomace    3,  30,  455,  481,  482 

Muriate  of  potash 3,  36,  37,  455,  488,  489 

Nitrate  of  soda  3,  13,  14,  455,  465 

Bradley's  Complete  manure  for  potatoes  and  vegetables. .  .3,  86,  87, 

455,  544,  545 
top     dressing     grass     and 

grain  3,  86,  87,  455,  540,  541 

Corn  phosphate 3,  96,  97,  455,  550,  551 

Eclipse  phosphate    3,  70,  71,  455,  524,  525 

Farmers  new  method  fertilizer. ..  .3,  66,  67,  455,  520,  521 

Niagara  phosphate    3,  72,  73,  455,  524,  525 

Potato  fertilizer   3,  92,  93,  455,  550,  551 

manure  3,  90,  91,  455,  548,  549 


9IO  INDEX. 

Page. 
American  Agricultural  Chemical  Co.,  cont'd — 

Church's  Fish  and  potash  3,  64,  65,  455,  522,  523 

Crocker's  Ammoniated  corn  phosphate  3,  go,  91,  4^,  548,  549 

Potato,  hop  and  tobacco  fertilizer.  .3,  92,  93,  455,  548,  549 

Darling's  Blood,  bone  and  potash. . .  .3,  60,  61,  455,  512,  513,  528,  529 

Dissolved  bone  and  potash.  .3,  62,  63,  455,  516,  517,  528,  529 

Farm  favorite   3,  68,  69,  455,  518,  519 

General  fertilizer  3,  72,  73,  455,  524,  525 

Potato  manure  3,  88,  89,  455,  544,  545,  554.  555 

East  India  A.  A.  Ammoniated  superphosphate  3,  66,  67,  455,  522,  523 

Potato  manure  3,  78,  79,  455,  540,  S41,  S42,  543 

Great  Eastern  General    3,  70,  71,  455,  516,  517 

H.     G.    vegetable,    vine    and    tobacco     fer- 
tilizer    3,  90,  91,  455,  544.  545 

Northern  com   special 3,  92,  93,  455,  546,  547 

Packer's  Union  Animal  corn  fertilizer  4,  92,  93,  456,  546,  547 

Gardeners  complete  manure.  .4,  62,  63,  456,  514,  515 

Potato  manure  4,  88,  89,  456,  542,  543 

Universal  fertilizer 4,  70,  71,  456,  520,  521 

Quinnipiac  Climax   phosphate    4,  y2,  ^z^  456,  524,  525 

Corn   manure    4,  90,  91,  456,  552,  553 

Market  garden  manure  4,  56,  57,  456,  510,  511 

Phosphate 4,  64.  65,  456,  518,  519 

Potato  manure  4,  88,  89,  456,  542,  543 

phosphate  4,  90,  91,  456,  546,  547 

Read's  Practical  potato  special    4,  98,  99,  456,  554,  555 

Standard  superphosphate    4,  70,  71,  456,  524,  525 

Vegetable  and  vine  fertilizer 4,  86.  87,  456,  546,  547 

Wheeler's  Bermuda  onion  grower  4,  100,  loi 

Corn   fertilizer    4,  98,  99,  456,  552,  553 

Havana  tobacco  grower  4,  100,  loi,  456,  531,  532,  536,  537 

Potato  manure    4,  94,  95,  456,  550,  551 

Williams    &    Clark's    Americus    Ammoniated    bone    super- 
phosphate 4,  68,  69,  456.  522,  523 

Corn  phosphate  4,  94,  95,  456, 

550,  551 

H.  G.  special  fertilizer.  .  .  .4,  62,  63, 

456,  516,  S17 

Potato  manure 4,  94,  95,  456, 

548,  549 

Potato  phosphate    4,  94,  95,  456,  548,  549 

Ammonia  water 704,  714 

analyses  of    706 

Anasa   tristis   805,  81 1 

Ancyhts  nubeculana    847 

Anisopteryx  pomcfaria    267,  778 

Anopheles    800,  801,  802,  804 


INDEX.  911 

Page. 

Anthonomus  signatus 846 

Anthracnose  of  meadowsweet  352 

of  string  beans 830 

of  white  oak  352 

Aphis  gossypii    805,  813 

pomi 267 

Aphis,  apple    267 

melon    805,  813 

squash    805,  814 

Apple  borer,   round-headed    333 

brandy,  analysis  of  712 

fruit  speck,  notes  on  340 

leaf- folder    847 

leaf-miner    267,  768 

leaf  rust 851 

rust    853 

scab,  notes  on 340 

spray,  injury  of    342 

Armour  Fertilizer  Works  : — 

All  soluble    4,  62,  63,  456,  518,  519 

Ammoniated  bone  with  potash 4,  68,  69,  74,  75,  456,  522,  523 

Bone,  blood  and  potash  4,  58,  59,  456,  512,  513 

Complete  potato   4,  90,  91,  456,  552,  553 

Corn   king 4,  86,  87,  456,  532,  546,  547 

Fish  and  potash   4,  60,  61,  456,  522,  523 

Fruit  and  root  crop  special  4,  78,  79,  456,  542,  543 

Grain  grower  4,  88,  89,  456,  552,  553 

High  grade  potato  4,  82,  83,  456,  542,  543 

Market  garden    4,  58,  59,  74,  75,  456,  514,  515 

Bone  meal  4,  42,  43,  456,  494,  495 

Artificial  color  in  catsup  129 

Ashes,  analyses  of  lime-kiln 114,  115,  567,  568 

miscellaneous     568 

from  household  fires,  composition  of  566 

of  rice  hulls,  analysis  of  117 

Asparagus,  injury  of,  bj'^  smoke  858 

Assassin  bug  822 

"Available  phosphoric  acid,"  explanation  of  term 33,  483 

Azalea,  powdery  mildew  of  859 

rust  of  854 

Bacillus  Delphini  862 

Bacterial  spot  of  larkspur    862 

peach   856 

lily 864 

poppy    870 

Bacterium  pruni  856 

tumefaciens  344 

64 


912  INDEX. 

Page. 

Bag-worm    337 

Baker,  H.  J.,  &  Bro.  :— 

Baker's  Castor  pomace 4,  30,  456,  481,  482 

Baldwin  spot,  notes  on   340 

Balm,  rust  of  bee   859 

Banding  trees    792-794 

Barley  products    726,  754,  755 

Barnyard,  analysis  of  wash  from  569 

Basic  slag  34 

Bean,  chlorosis  of  Lima   343 

Beans,  chlorosis  of   859 

Beef,  wine  and  iron  673 

analyses  of   676-679 

claims  of  manufacturers  of  682 

discussion  of  analyses  of  680 

methods  of  analysis  of  685 

volume  and  selling  price  of  675 

Beet  pulp    175,  733 

refuse,  analysis  of  568 

Beetle,  a  fungus-inhabiting 337 

Beets,  dampening  off  of   860 

Bellflower,  rust  of   343 

Benzoic  acid  in  catsup   129 

Berkshire  Fertilizer  Co. : — 

Berkshire  Ammoniated  bone  phosphate  4,  72,  73,  456,  524,  525 

Complete   fertilizer  4,  62,  63,  456,  514,  515,  516,  517 

Grass  special    4,  84,  85,  456,  544,  545 

Long  Island  special 56,  57,  456,  514,  515 

Potato  and  vegetable  phosphate   .  .4,  96,  97,  456,  550,  551 

Tobacco  special    4,  82,  83,  456,  530,  538,  539,  544,  545 

Fine  ground  bone   4,  41,  42,  43,  456,  494,  495 

Bitter  rot  of  currant  347 

Bittersweet,  crown  gall  of  Japanese  3-44 

Blackberry,  rust  of   344 

Black  potash,  analysis  of   487 

Blight  of  pine 353 

Board  of  control,  report  of  ix 

Boardman,  F.  E. : — 

Boardman's  Complete  fertilizer  4,  56,  57,  456,  510,  511 

Bohl,  Valentine: —  .  . 

Self-recommending  fertilizer    4,  42,  43,  456,  494,  495 

Boletotherus   hifurcus    337 

Bone  black,  analysis  of  120 

manures    39,  491 

guaranties  of 41,  493 

analyses  of    42,  43,  494,  495 

cost  and  valuation  of  41,  493 


INDEX.  913 

Page. 

Bone,  method  of  valuation  of  40,  493 

Borax    710 

Borer,  maple    336 

poplar   335 

round-headed   apple    333 

Botanist,  report  of    339,  849 

Bowker  Fertilizer  Co. : — 

Castor  pomace    5,  30,  456,  481,  482 

Muriate  of  potash   5,  36,  37,  456,  488,  489 

Nitrate  of  soda 5,  13,  14,  456,  465 

Bowker's  Acid  phosphate    4,  32,  33,  457,  483,  484 

Complete  alkaline  tobacco  grower    4,  104,  105,  457, 

558,  559 

Corn  phosphate 4,  100,  loi,  457,  554,  555 

Early  potato  manure   5,  90,  91,  457,  546,  547 

Farm  and  garden  phosphate  5,  72,  73 

Fine  ground  fish   5,  44,  47,  457,  498,  499 

Fisherman's  brand  fish  and  potash  5,  68,  69,  457,  520,  521 

Fresh  ground  bone  5,  42,  43,  457,  494,  495 

Gloucester  fish  and  potash  5,  72,  'j'i,  457,  526,  527 

Hill  and  drill  phosphate  5,  66,  67,  457,  524,  525 

Lawn  and  garden  dressing   5,  100,  loi,  457,  554,  555 

Market  garden  fertilizer    5,  64,  65,  457,  520,  521 

Middlesex  special   5,  70,  71 

Potato  and  vegetable  fertilizer 5,  94,  95,  457,  550,  551 

Potato  and  vegetable  phosphate  ...  5,  98,  99,  457,  554,  555 

Pure  unleached  Canada  hard  wood  ashes   5,  112,  113, 

457,  462,  564,  565 

Sure  crop  phosphate 5,  72,  73,  457,  526,  527 

Tobacco  ash  elements   5,  104,  105,  457,  558,  559 

starter    5,  90,  91,  457,  548,  549 

XX  bone   5,  42,  43,  457,  494,  495 

Stockbridge  Special  complete  manure  for  corn  and  grain  .  .5,  86,  87, 

457,  540,  541 
Special    complete    manure    for    potatoes    and 

vegetables    5,  88,  89,  457,  540,  541 

Special  complete  manure  for  top  dressing  and 

for  forcing   5,  84,  85,  457,  538,  539 

Tobacco  manure   ■.  .5,  82,  83,  457,  538,  539 

Brainard,  H.  K. : — 

"High  Grade"   5,  56,  57 

Brewers'  grains,  dried  177,  204,  205,  727,  754,  755 

Brown-tail  moth    313 

new  law  regarding 308 

Buckwheat  flour  127 

Buckwheat  products    175,  202,  203,  726,  754,  755 


914  INDEX. 

Page. 
Buffalo  Fertilizer  Co. : — 

Buffalo  Tobacco  producer 5,  78,  79,  100,  loi,  457,  462 

Celery  and  potato  special  5,  ^^,  96,  97,  100,  loi,  457,  540,  541 

Farmers'  choice    5,  48,  49,  50,  72,  73,  457,  514,  515 

Fish  guano    5,  70,  71,  457,  512,  513 

Garden  truck   5,  48,  49,  50,  62,  63 

H.  G.  manure  (or  fertilizer)    100,  loi,  457,  501,  512,  513 

Ideal  wheat  and  corn 5,  76,  77.  96,  97,  457,  538,  539 

Top  dresser    5,  48,  49,  66,  67,  72,  73,  457,  510,  511 

Vegetable  and  potato   5,  76,  TJ,  94,  95,  98,  99,  457,  538,  539 

Bone    meal    5,  41,  42,  43,  457,  494,  495 

Floats   486 

Acid  phosphate  483,  484 

Muriate  of  potash  5,  36,  zi,  488,  489 

Nitrate  of  soda 5,  I3,  I4 

Butter  and  butter  substitutes 162,  713 

Cabbage  butterfly   768 

maggot,  treatment  to  prevent 832-83^ 

Caeoma  Abietis-Canadensis    350,  389,  390,  391 

Abietis-pectinatae    389 

Calosoma  calidum    786 

scrutator     786 

Calyptospora  columnaris   393 

goeppertiana 385,  391 

Canker  worm   769,  777-796 

description    782 

fall    783 

spring  782 

natural  enemies    786 

postal  card  bulletin  on 767 

remedies    786-792 

summary     794 

Carbon  disulphide    797 

used  against  peach  sawfly 292 

for  fumigation   272 

tetrachloride   798 

used  for  fumigation 275 

Carum  copticum,  analysis  of  733 

Castor  pomace,  analyses  of 30,  481 

Catarrh  remedies  714 

Catsup    129 

Cercospora  Dolichi   346 

sordida    362 

Chestnut  bark  disease  345,  852 

character  of  880 

distribution  in  Connecticut  881 

future  outlook 889 


INDEX.  915 

Page. 

Chestnut  bark  disease,  general  distribution  880 

general  statement  concerning 879 

relation  to  weather  887 

the  fungous  agent  885 

trees  injured  by  beetles   845 

Chili  sauce  129,  713 

Chionaspis  pinifoliae    335 

Chlorine,  used  for  fumigation  277 

Chlorosis  of  bean    343,  859 

muskmelon   865 

tomato   857 

Chocolate    134,  713 

compound 135 

sweet 135 

Chrysanthemum,  rusted  86x 

Chrysobothris   femorata    333 

Chrysomyxa  Abietis  389,  391 

albida  383,  385 

Pyrolae    3^ 

Chrysopa  sp ' 822 

Cinnamon  IS7 

Clark  Seed  Co.,  Everett  B. : — 

Clark's  Special  mixture  for  general  use  5,  54,  56,  57,  457,  500,  501, 

510,  511,  512,  513 

Special  10%  brand   60,  61,  457,  510,  511,  526,  527 

Clover  worm,  green    769,  828 

description    830 

remedies    832 

Cloves    155-  157 

Cocoa    134 

Coe-Mortimer  Co. : — 

Genuine  Peruvian  guano,  Chincha  grade  6,  60,  61,  457,  500,  508,  514, 

515,  528,  529 

Lobos  grade 6,  60,  61 

Gold  brand  excelsior  guano  5,  50,  66,  67,  457,  518,  519 

H.  G.  ammoniated  bone  superphosphate 5,  70,  71,  457,  516,  517 

Peruvian  market  garden  fertilizer  6,  48,  50,  68,  6g 

Peruvian  tobacco  fertilizer   6,  75,  84,  85,  88,  89 

Tobacco  and  onion  manure 457,  538,  539 

E.  Frank  Coe's  Celebrated    special    potato    fertilizer    5,  94,  95,  457, 

536,  537 
New  Englander  corn  and  potato  fertilizer  5,  98,  99, 

457,  550,  551 
Peruvian   vegetable    grower   6,  50,  62,  62,  457,  536, 

537 
Red   brand    excelsior    guano    5,  48,  50,  64,  65,  458, 

512,  513 


91 6  INDEX. 

Page. 

Coe-Mortimer  Co.,  cont'd — 

E.  Frank  Coe's  XXX  pure  ground  bone 6,  42,  43,  458,  494,  495 

H.  G.  sulphate  of  potash  488,  489 

Acid  phosphate  483,  484 

Muriate  of  potash  488,  489,  490 

Nitrate  of  soda 13,  14 

Tankage 496,  497 

Cofifee    137,  713 

hygienic    141 

Coleosporium  Campanulae    343,  374 

Helianthi  394 

Senecionis  394 

Solidaginis 375,  376 

Vernoniae   380 

Commercial   feeds,   average  composition,   digestibility  and   selling 
price, 735 

Commercial  feeds,  containing  weed  seeds    736 

Connecticut  Fat  Rendering  and  Fertilizing  Corporation: — 

Tankage   6,  41,  45,  458,  496,  497 

Connecticut  Valley  Orchard  Co. : — 

C.  V.  O.  Co.'s  H.  G.  special  ...6,  56,  57,  74,  75,  458,  508,  510,  511, 

526,  527,  528,  529 

Contents,  table  of v 

Cooper's  Glue  Factory,  Peter : — 

Pure  bone  dust  6,  42,  43,  458,  494,  495 

Coi-n  and  oat  feeds  178,  204,  205,  728,  754-757 

breeding  at  present  in  progress   400 

practical  use  of  Mendelism  in  407 

ear-worm  or  boll-worm   847 

Corn,  caring  for  seed    401 

dent-sweet  crosses   41 1 

flint-dent  crosses 41 1 

flint-sweet  crosses    410 

germination  tests   403 

inbreeding  of 419 

inheritance  of  characters  in 407 

oats  and  barley 179,  206,  207 

prospects  for  better  seed 397 

purple-white  crosses   413 

purchase  of  seed  405 

red-white  crosses  415 

summary  of  law  of  inheritance 416 

yellow-white  crosses   412 

Corrections  and  additions    xxiii 

Cotton  hull  ashes,  analyses  of  109,  560 

"Cotton  hulls,"   analyses  of  charred  no 

Cotton  seed  meal    IS,  169,  192,  193,  466,  717,  742,  743 


INDEX.  917 

Page. 

Cotton  seed  meal,  composition  and  value  of  19,  469 

guaranties   18,  468 

standard  classification  of   16,  467 

tables  of  analyses  of  22-29,  470-480 

Cow  pea,  leaf  blight  of  346 

Cream,  analyses  of   162,  712 

Cream  of   tartar    138 

Creatin,  method  of  determining  614 

Creatinin,  method  of  determining  613 

Cronartium  asclepiadeum    382 

Comandrae   394 

Comptoniae    353,  380 

ribicola    394 

Crown  gall  of  bittersweet 344 

Cryptorhynchus  lapathi 335 

Cucumber  beetle,  striped 805,  807 

Culex    800,  801,  802,  804 

Curcurbits,  insects  attacking 805 

Currant,  bitter  rot  of  347 

powdery  mildew  of  348 

Currant   worm    768 

Cuterebra   ciiniculi    338 

Cylindrosporium  Filipendulae   352 

Dahlia,  dry  weather  injury  of   861 

Dairy  and  stock  feeds,  proprietary   180,  206-209,  729,  756-759 

Dampening  off  of  beets  860 

sweet  pea 359 

Dandelion,  leaf  spot  of  862 

Dennis,  George  L. : — 

Bone    6,  42,  43,  458,  494,  495 

Diabetic  flour,  analyses  of  , 712 

foods     138,  71 1 

Diabrotica  xii-pimctata    805,  809 

vittata    805,  807 

Diaporthe  parasitica   345,  879 

Dissolved  rock  phosphate,  analyses  of   31,  483 

Distillery  grains,  dried   176,  202,  203,  726,  754,  755 

Downy  mildew  of  gourd  862 

grape    854 

Dried  blood,  analyses  of  15,  465 

brewers'  grains  177,  204,  205,  727,  754,  755 

Drop  of  lettuce  863 

parsley    868 

Drugs,  summary  of  results  of  examination  of 715,  716 

Eldredge,  T.  H.  :— 

Eldredge's  Special  fish  and  potash  fertilizer  6,  70,  71,  458,  524,  525 
superphosphate   6,  72,  73,  458,  524,  525^ 


9l8  INDEX. 

Page. 

Elm  leaf  beetle     337,  767,  769,  815-828 

description    818 

natural  enemies    821 

outfit  for  spraying  825 

remedies    823 

summary   827 

Ennomos  subsignarius   842 

Ensilage,  analyses  of  maize 721 

Entomological  features  of  1907   267 

1908    768 

Entomologist,  report  of 266,  763 

Epilachna    borealis    805,  810 

Eriophyes  pyri    770 

Erysiphe  dehor acearum  867,  871 

Polygoni    349 

Essex  Fertilizer  Co. : — 

Essex  A  I  Superphosphate  8,  72,  72 

Complete,  potatoes,  roots  and  vegetables  8,  80,  81,  458,  530, 

546,  547 

Corn,  grain  and  grass  8,  82,  83,  458,  531,  548,  549 

Grass  and  top  dressing  8,  80,  81,  458,  532,  550,  551 

Market  garden  and  potato  manure  ...8,  92,  93,  458,  552,  553 

Special  tobacco  manure   8,  78,  79,  458,  540,  541 

Tobacco  starter 8,  90,  91 

and  grower 458,  548,  549 

XXX  fish  and  potash   8,  64,  65,  458,  520,  521 

Dry  ground  fish  8,  44,  47,  458,  498,  499 

Ground  bone    458,  494,  495 

Estigmene  acraea 843 

Eumenes  fraternns    786 

Euproctis  chrysorrhaea    , 313 

Euvanessa   antiopa    267,  768 

Fall  canker  worm   267 

Feeding  stuffs,  digestibility  of    183,  735 

explanations  of  analyses  of 166 

law  regulating  sale  of 165 

sampling  of  commercial   166 

uses  of  analyses  of  168 

weight  of  one  quart  of  various   189,  762 

Fern,  leaf  scorch  of 349 

Fertilizer  elements,  trade  values  of  39.  49-2 

law,  observance  of  2,  454 

Fertilizers,  analyses  of    ii,  463 

classification  of    12,  464 

duties  of  manufacturers  and  dealers i,  453 

method  of  valuation  of  39>  49i 

on  which  analysis  fees  have  been  paid,  list  of  — 3,  455 


INDEX.  919 

Page. 

Fertilizers,  sampling  and  collection  of  10,  462 

selection  and  purchase  of  commercial 52,  503 

Fish,  analyses  and  valuations  of  46,  500 

of  dry  ground  44  47,  496,  499 

guaranties  of 46,  498 

Flax  feed  and  flax  flakes  179,  206,  207,  727,  756,  757 

Floats,  value  of  485 

Food  products,  summary  of  results  of  examination  of  715,  716 

work  in  1907  163 

1908  715 

Forester,  report  of   211 

Forest  plantations    211 

in  Conn,  older   251 

recent    242 

private  248 

planting  experiments,  description  of  213 

map  of   228 

summary  of    230 

visitor's  guide  to    228 

plantings  by  educational  institutions  246 

Forests,   state    242 

Frisbie,  L.  T.,  Co. : — 

Frisbie's  Fine  bone  meal   6,  42,  43,  458,  494,  495 

Fruit  preserves  581 

Fumigating  nursery  stock  for  San  Jose  scale  796 

with  gases,  tests  270 

Fungous  diseases,  of  1907,  notes  on  339 

of  1908,  notes  on  849 

Galerucella  liiteola  337,  815 

Gases  for  fumigation,  tests  of  270 

Germof ert  Mfg.  Co. : — 

Germofert  Patented  fruit  and  flower  fertilizer 458,  534,  535 

General  fertilizer  458,  512,  513 

Vegetable  fertilizer  458,  534,  535 

Natural  plant  food   528,  529 

Ginger    156,  iS7,  7I3 

ground    574 

Gloeosporium  canadense   352 

nervisequum     360 

ribicoluni    348 

Ribis  347 

rufo-maculans    347 

Gluten  feed    172,  198-201,  722,  748-751 

acidity  of    723 

artificial  color  in 722 

meal,  analysis  of  118 

Golden-rod  devoured  by  beetles  844 

65 


920  INDEX. 

Page. 

Goodsell.  W.  O.  :— 

Special  grass  mixture  458,  532,  534,  535 

Gourd,  downy  mildew  of 862 

Grape,  downy  mildew  of    854 

powdery  mildew  of  , 855 

Grape  vine  flea  beetle 337 

Gummosis  of  peach 869 

Gymnosporangium  clavipes    351 

macropus    853 

Gypsy  moth,  control  work   300 

funds  for  work   307 

Gypsy  moth    in  Connecticut  7^7 

infested  localities  near  Connecticut  776 

legislation  concerning  307 

in  other  states   310 

new  law  regarding   308 

parasites    311 

present  condition  at  Stonington  776 

scouting  for  egg-masses — Eastern  Connecticut  774 

Hartford    774 

New   Haven  to   Hartford  775 

Stonington     773 

statistics    306 

suppression  work 77^-777 

funds     77^ 

summary   777 

Halisidota  caryae    332,  843 

tessellaris    843 

Haltica   chalybea    337 

Headache  powders    7^4 

analyses  of 692-705 

preparations 686 

methods  of  analysis  of   688 

Heliothis  obsoleta 847 

Hemlock,  rust  of  350 

Heterocampa  guttivitta    848 

Heteroecism   370 

Hickory  tussock  caterpillar 842 

moth 332 

Home  mixtures    107,  559 

analyses  of    106,  107,  s6o,  561 

Hominy  feed    I74,  200-203,  725,  750-753 

Honey    I39,  162 

compound    I39 

Hops,  analyses  of  spent  733 

Horse  feeds,  proprietary  180,  206,  207,  729,  756,  757 

"Humus  Fertilizer,"  analysis  of  570 


INDEX.  921 

Page. 

Hydrocyanic  acid  gas,  used  for  fumigating 280 

Ichneumon  utilis    786 

"I.  M.  P.  Plant  Food,"  analysis  of lig 

Indigo,  powdery  mildew  of  false 349 

Infant  and  invalid  foods,  methods  of  analysis  of  601 

tables  of  analyses  of 602-605 

foods    599 

Insect  notes   842 

notes,  miscellaneous  334 

Invalid  foods  599 

Iodine,  tincture  of  707,  714 

Ithycerus  noveboracensis  845 

James,  Ernest  L. : — 

James'  Bone   phosphate    6,  74,  75,  458,  526,  527 

Ground  bone    6,  42,  43,  458,  494,  495 

Jams  581 

and  jellies,  the  labeling  of  compound  582 

Jellies   581 

Jelly  powder   583 

Julus  hortensis   337 

June  berry,  rust  of  351 

Kainit,  analyses  of  38,  490 

Kelsey,  E.  R.  :— 

Bone,  fish  and  potash  ..6,  56,  57,  74,  75,  458,  509,  510,  511,  526,  527 

"Kill-o-Scale"    282 

Kuehneola  albida  344,  372,  383,  384,  385 

Lard    143 

compound    144 

Larkspur,  bacterial  spot  of  862 

Laurel,  leaf  spot  of  351 

Laws  regarding  foods  and  drugs  121 

Lead  arsenate ySj,  823 

Lead  arsenate,  analyses  of 323 

chemical  composition  of   321 

vs.  Paris  gi-een  843 

Leaf  blight  of  cow  pea  346 

trumpet-creeper    362 

scorch  of  fern   349 

spot  of  dandehon  862 

laurel 351 

rhododendron  871 

Lehia  grandis   844 

Lema  trilineata  844 

Lemon   extract    144,  713 

Leopard  moth   847 

Leptinotarsa   decemlineata    768 

Lettuce,  drop  of  ^ 863 


92  2  INDEX. 

Page. 

Liebig  process  for  meat  extract  606 

Lily,  bacterial  spot  of  864 

Limb-gall  of  oak  866 

Lime,  analyses    of    114,  115,  567,  568 

carbonate  of   567,  568 

Lime  and  sulphur  washes,  various  kinds  840 

Linseed  meal    170,  192,  193,  718,  742,  743 

analysis  of 31 

Lister's  Agricultural  Chemical  Works : — 

Lister's  Ammoniated  dissolved  bone  phosphate  6,  64,  65,  458,  514,  515 

Potato   manure    6,  82,  83,  458,  530,  531,  538,  539 

Special  corn   6,  86,  87,  458,  552,  553,  554,  555 

potato   6,  86,  87,  458,  462 

tobacco   6,  96,  97,  458,  531,  544,  545 

Standard  pure  bone  superphosphate  of  lime  6,  62,  63,  458, 

516,  517 

Success   fertilizer    6,  66,  ^"j,  458,  522,  523 

Animal  bone  and  potash  458,  524,  525 

Bone  meal 6,  42,  43 

Celebrated  ground  bone  acidulated  458,  494,  495 

Little  peach   869 

Maize  ensilage    721 

meal    , 172,  721 

Malt  sprouts   176,  202,  203,  754,  755 

Manchester,  E.,  &  Sons : — 

Manchester's   formula    6,  56,  57,  459,  500,  510,  511 

Manure,  analysis  of  shredded  116 

Mapes  F.  &  P.  G.  Co.  :— 

Average  soil  complete  manure    6,  58,  59,  459,  514,  515 

Cereal  brand  6,  98,  99,  459,  554,  555 

Complete  manure  "A"  brand  6,  70,  71,  459,  522,  523 

Corn  manure    6,  92,  93,  459,  552,  553 

Economical  potato  manure   6,  84,  85,  459,  544,  545 

Fruit  and  vine    6,  94,  95,  459,  552,  '553 

Potato  manure  6,  86,  87,  459,  542,  543 

Seeding  down  manure 6,  80,  81,  459,  536,  537 

Tobacco  ash  constituents  6,  104,  105,  459,  558,  559 

manure,  wrapper  brand 6,  104,  105,  459,  558,  559 

starter,  improved 6,  84,  85,  459,  558,  559 

Top  dresser,  improved,  full  strength  7,  56,  57,  459,  510,  511 

half       "  7,  66,  67,  459,  516,  S17 

Vegetable  manure,  or  complete  manure  for  light  soils  7,  60,  61,  459, 

512,  513 

Dissolved  bone    6,  56,  57,  459,  512,  513 

Maple,  black  spot  of  852 

Maple  borer 336 

syrup 150,  712,  713 


INDEX.  923 

Page. 

Marine  mud,  analysis  of  119 

Meadowsweet,  anthracnose  of  352 

Meat  extracts 606 

analyses  of  fluid 642 

chlorine  in  fluid  643 

claims  of  manufacturers  of  fluid  647 

discussion  of  claims  of  the  manufacturers  of 634 

fluid    640 

fluid,  statement  of  brands  found  pure,  misbranded 

or  adulterated  651 

how  to  value  ■ 609 

methods  of  analysis  of 611 

net  weight  and  selling  price  of  615 

nitrogenous  constituents  of  fluid   644 

paste   614 

phosphoric  acid  in  624 

physiological  effect  of   607 

potash  in  624 

preservatives  in    633 

in  fluid   647 

review  of  literature  of  664 

sodium  chlorid  in 622 

standards  of  composition  of 609 

statement  of   brands   found  pure,  misbranded   or 

adulterated 639 

table  of  chemical  analyses  of  ^ . . .  618-621 

the  meat  bases  in , 629 

fluid 646 

the  nitrogenous  constituents  of  625 

juices    652 

powders  and  meat  capsules   659 

preparations     606 

fluid  proprietary   655 

scrap    182,  208,  209,  732 

Melampsorella  Caryophyllaceum    394^ 

elatina    394 

Melampsoridium  Betulae 386 

Melampsoropsis  Cassandrae    373,  386 

Pyrolae    373,  388,  393 

Melittia  satyriniformis  805,  806 

Mendelism  in  corn  breeding,  practical  use  of  406 

Mendel's  law  of  inheritance 408 

Microgaster    .* 786 

Microrophala  vittata  844 

Microsphaera  Aim    859,  866,  868 

Milk   162,  712,  713 

analysis  of  dried   734 


924  INDEX. 

Page. 

Mites    770 

Molasses    162,  713 

analysis  of  183 

grains    179,  206,  207,  731 

Monophadnoides  rubi  846 

Mosquito  breeding  conditions    318 

Mosquito  work,  Beaver  Swamp  802 

East  Haven  rifle  range 800 

Stamford 804 

Muck,  analyses  of  swamp  569 

Muskmelon  chlorosis    865 

Mustard    156,  157,  714 

Myriapod,  an  injurious   2>Z7 

National  Fertilizer  Co. : — 

Chittenden's  Ammoniated  bone  phosphate   7,  10,  459,  526,  527 

Complete  fertilizer 7,  62,  63,  459,  518,  519 

tobacco    7,  84,  85,  100,  loi 

Connecticut  Valley  tobacco  grower    ...7,  104,  105,  459, 

558,  559 

starter   7,  80,  81,  459, 

536,  537 

Fish  and  potash  7,  60,  61,  459,  518,  519 

Formula  "A"   7,  56,  57,  459,  512,  513 

"B"    7,  58,  59,  459>  462 

H.  G.  special  tobacco  fertilizer  7,  yy,  80,  81,  459, 

536,  537 

Market  garden  fertilizer  7,  64,  65,  459,  518,  519 

Potato  phosphate   7,  86,  87,  459,  540,  541 

special    459,  546,  547 

Tobacco  special  with  carbonate  of  potash  ..7,  104,  105, 

459,  558,  559 

XXX  fish  and  potash 7,  56,  57,  459,  514,  515 

Soluble  bone  and  potash 7,  70,  71,  459,  526,  527 

Dry  ground  fish   7,  46,  47,  459,  498,  499 

Nitrate  of  soda 13,  14,  459,  465 

Dried  blood   466 

Castor  pomace    481,  482 

Necium  Farlowii   389 

Nectarophora  cuciirbitae  805,  814 

New  England  Fertilizer  Co. : — 

New  England  Com  and  grain  fertilizer  ...7,  100,  loi,  459,  554,  555 

H.  G.  potato  fertilizer  7,  88,  89,  459,  546,  547 

Perfect  tobacco  grower 7,  104,  105,  459,  540,  541 

Potato  fertilizer  7,  96,  97,  459,  554,  555 

Superphosphate     7,  64,  65,  459,  518,  519 

Ground  bone  7,  42,  43,  459,  494,  495 

Muriate  of  potash 488,  489 

Tankage   496,  497 


INDEX.  925 

Page. 

New  Jersey  tea,  powdery  mildew  of  866 

Niantic  Menhaden  Oil  &  Guano  Co. : — 

Bone,  fish  and  potash  459,  514,  515 

Nitrate  of  soda,  analyses  of 13,  464 

Nodonota   puncticollis    845 

North  Western  Fertilizing  Co. : — 

North  Western  Bone,  fish  and  potash  459,  518,  519 

Empire  special  manure   7,  58,  59,  459,  510,  511 

Market  garden  phosphate    ..7,  60,  61,  459,  518,  519 

Superphosphate    7,  60,  61,  459,  514,  515 

10%  manure   7,  56,  57,  459,  510,  511 

10%  potato    fertilizer    7,  92,  93,  459,  550,  551 

Universal  fertilizer   459,  518,  519 

Nothrus   ovivoriis    786 

Nursery  firms  receiving  certificates  in  1907  269 

1908   771 

inspection    268,  765,  770 

Oak,  anthracnose  of  white  , 352 

limb-gall  of    866 

Ogdoconta  cinereola   828 

Ohio  Farmers  Potato  and  Tobacco  Special 77,  92,  93 

Okra,  powdery  mildew  of 867 

Olds  &  Whipple:— 

O.  &  W.'s  Complete  tobacco  fertilizer   ....7,  104,  105,  460,  558,  559 
Corn   and   potato    fertilizer    7,  82,  83,  100,  loi,  460,  536, 

537 

Fish  and  potash   460,  516,  517 

Grass   fertilizer    7,  82,  83,  460,  540,  541 

H.  G.  potato  fertilizer  7,  82,  83,  460,  536,  537 

Special   phosphate    .7,  62,  63,  460,  510,  511 

Dry  ground  fish  460,  498,  499 

Grey  pomace   7,  30,  460,  481,  482 

Vegetable  potash    7,  108,  460,  487 

Precipitated  bone  34,  485 

Carbonate  of  potash 486,  487 

Olive  oil    151,  714 

analyses  of   151 

O  tiorynchus  sulcatus    846 

Pagoda  tree,  powdery  mildew  of  868 

Paleacrita  vernata   782,  794 

Pamphilius  persicum  285,  767 

Paris  green    767,  824 

analyses  of  328 

chemical  composition  of   321,  326 

Parmenter  &  Polsey  Fertilizer  Co. : — 

"A.  A."    brand    7,  58,  59,  460,  462 

Plymouth  Rock  brand  7,  64,  65,  460,  516,  517 


926  INDEX. 

Page. 
Parmenter  &  Polsey  Fertilizer  Co.,  cont'd-^ 

Special  potato  fertilizer  7,  88,  89,  460,  462 

Star   Brand    7,  10 

P.  &  P.  Potato    fertilizer    7,  98,  99,  460,  552,  553 

Ground  bone   7,  42,  43,  460,  494,  495 

Muriate  of  potash  460,  488,  489 

Nitrate  of  soda  I3>  i4 

Parsley,  drop  of  868 

Peach,  bacterial  spot  of  856 

collar  girdle  856 

gummosis    869 

injury  from  droughts  874 

leaf-fall  of 342 

httle 869 

sawfiy  285,  767 

description    295 

yellows     872 

preventive  measures    877 

theories  concerning  875 

winter  injury 873 

Peanut  refuse  183 

Pear  injured  by  weevil 843 

Peas  and  beans,  ground I75 

Peat,  analyses  of ' 569 

Pegomyia  brassicae  832 

Pepper,  black   I54,  i55,  i57,  7i3 

white    156,  157 

Percentage  difference,  explanation  of  5I)  502 

Peridermia,  literature  of   394 

relationships  of  37i 

Peridermium  acicolum    374.  375 

balsameum 392,  393,  394 

columnare    393 

conorum  Piceae  388 

■    consimile    386 

elatinum  394 

Laricis    386 

oblongisporhim    : . .  375.  394 

Peckii    350,  383,  384,  391,  394 

Pini   375 

pyriforme •  •  353,  380 

Rostriepi   374 

Strobi    394 

Per 0110 plasmopora  cubensis   862 

Phellomyces  sclerotiophoriis    358 

Phragmidium  speciosum    359 

siibcorticium    359 


INDEX.  927 

Page. 

Phyllosticta  maxima  871 

Pteridts 350 

Phytophthora,  artificial  cultures  of  with  reference  to  oospores  . . .  891 

Phytophthora  infestans    891,  893,  894,  895,  900 

cross-cultures    899 

cultural  methods  897 

hybrid  (?)  cultures   900 

life  history 895 

media    898 

Nicotianae    891 

Phaseoli    891,  893,  894,  900,  901 

attempts  to  lose  oospores  906 

cultural  methods    903 

life  history  901 

media    904 

Thalictri   893 

infection  experiments    895 

life  history    894 

Pine  blight  353,  852 

leaf  scale  on  hemlock  334 

rust  of  white 353 

Pines  for  forest  planting   212 

Plagionotus  speciosus  33^ 

Plant  lice   77^ 

Plasmopara  viticola  854 

Plathypena  scabra  769,  82S 

Platygaster 786 

Platynus  punctiformis    822 

Podisus  maculiventris   (spinosiis)    769,  822 

Pontia  rapae   7^8 

Poplar  borer   335 

Poppy?  bacterial  spot  of  870 

Potash,  analyses  of  carbonate  of    35,  486 

double  sulphate  of  35,  36,  488-490 

high  grade  sulphate  of  35,  36,  487,  488 

muriate  of  36-38,  488-490 

Potato  beetle 768 

breeding,  some  assential  points  in 429 

Potato,  characters  of  pollen   435 

correlations  between  characters    443 

description  of  flowers   435 

growth  of  the  seed  berry  440 

internal  brown  spot  of  355 

notes  on  tip-burn  of  34^ 

scurf  of 357 

summary  of  procedure  in  hybridizing 442 

variety  variation  in  flowering  430 


928  INDEX. 

Page. 

Potter  wasp 786 

Poultry    feeds,    proprietary    181,  208,  209,  731,  760,  761 

Powdery  mildew  of  azalea    859 

currant  348 

false  indigo   349 

grape  855 

New  Jersey  tea 866 

okra    867 

pagoda  tree   868 

sunflower    871 

Praying  mantis    822 

Precipitated  bone,  analyses  of  34,  485 

Preservatives  in  meat  extracts   633 

fluid  meat  extract  647 

Preserves,  fruit 581 

Priophorus  acericaulis   298 

Proteoses,  method  of  determining  613 

Pseudomonas  Pruni   856 

Pseudopesiza  Ribis 347 

Pteronus  ribesii  768 

Pterostichus  lucuhlandus  844 

Puccinia  Chrysanthemi 861 

Helianthi  871 

Menthae 859 

Pucciniastrum  Agrimoniae    391 

arcticum  americanum 391,  393,  394 

balsameum  394 

minimum    '. 392,  854 

Myrtilli   394 

pustulatum  • 392,  393 

Pyrolae  393 

Vacciniorum 394 

Purin  bases,  method  of  determining 614 

Pyramidal  caterpillar   848 

Pyrophila  pyramidoides  848 

Pythium  sp 359 

Quedius  molochinus   822 

Quince,  rust  of  851 

Rabbit  bot-fly 338 

Radish,  spindling  of 871 

Ramularia   Taraxici    862 

Raspberry  syrup  585 

Red  dog  flour  720,  748,  749 

Reduvius   novenarius    822 

Report  of  agronornist    397 

board  of  control  ix 

botanist    339,  849 


INDEX.  929 

Page. 

Report  of  entomologist    266,  763 

forester    211 

treasurer    xix,  xxi 

on  feeding  stuffs    165,  ivj 

fertilizers    i,  453 

food  products  121,  573 

Rhizoctonia  sp 359 

Rhododendron,  leaf  spot  of  871 

Rhytisma  acerinum   852 

Rice  feed   734 

products    I75>  202,  203 

Roestelia  aurantiaca 35i)  831 

pirata    851,  853 

Rogers  &  Hubbard  Co. : — 

Hubbard's  Complete  phosphate   7.  68,  69,  460,  520,  521 

Fertilizer  for  oats  and  top  dressing  7,  78,  79,  460,  536, 

537 

Grass  and  grain  fertilizer   8,  80,  81,  460,  540,  541 

Market  garden  fertilizer  8,  58,  59 

Potato  phosphate 8,  86,  87,  460,  538,  539 

Soluble   corn   and   general   crops   manure  8,  62,  63,  460, 

516,  517 

potato  manure   8,  80,  81,  460,  534,  535 

tobacco  manure  8,  80,  81,  460,  534,  535 

Pure  raw  knuckle  bone  flour 8,  42,  43,  460,  494,  495 

Strictly  pure  fine  bone 8,  42,  43,  460,  494,  495 

Rogers  Mfg.  Co. : — 

All  round   fertilizer    8,  48,  64,  65,  68,  69,  460,  522,  523 

Corn  and  onion   8,  78,  79,  460,  531,  532,  536,  537 

Fish  and  potash    8,  66,  67,  460,  500,  518,  519 

Grass  and  grain 8,  78,  79,  460,  534,  535 

H.  G.  soluble  tobacco  8,  78,  79,  100,  loi,  460,  534,  535 

Oats  and  top  dressing  8,  78,  79,  100,  loi,  460,  529,  534,  535 

Potato  and  vegetable    8,  88,  89,  460,  538,  539 

Tobacco  and  potato  8,  82,  83,  460,  534,  535 

grower  8,  80,  81,  460,  530,  534,  535 

starter   8,  84,  85,  460,  544,  545 

Fine  ground  bone  8,  42,  43,  460,  494,  495 

Knuckle  bone  flour  8,  42,  43,  460,  494,  495 

Black  potash   487 

Tankage 496,  497 

Root  rot  of  tobacco    363 

method  of  sterilizing  seed  beds   364 

Rose,  rust  of  359 

Russia  Cement  Co see  Essex  Fertiliser  Co. 

Rust  of  apple    853 

azalea    854 


930  INDEX. 

Page. 

Rust  of  bee  balm 859 

bellflower   343 

blackberry    344 

chrysanthemum    861 

hemlock    350 

June  berry 351 

rose    359 

sunflower  871 

white  pine   353 

Rusts,  Heteroecious  of  Connecticut  having  a  peridermium 369 

Rye  products  174,  202,  203,  726,  752-755 

Salt,  Cerebos 595 

Ivory  Compound 598 

Shaker    598 

table 586 

Salt-waste,  analysis  of  118 

Saltpeter  waste,  analysis  of  118 

Sanderson  Fertilizer  &  Chemical  Co. : — 

Atlantic  Coast  bone,  fish  and  potash    8,  66,  67,  460,  522,  523 

Sanderson's  Corn    superphosphate    8,  94,  95,  460,  546,  547 

Formula  A    8,  60,  61,  460,  512,  513 

B    for   tobacco   8,  82,  83,  84,  85,  100,  loi,  460, 

538,  539,  554,  555 

Potato  manure  8,  96,  97,  460,  544,  545 

Special  with  10%  potash  8,  50,  68,  69,  460,  512,  513 

Top  dressing  for  grass  and  grains  8,  84,  85,  460,  546, 

547 

Fine  ground  bone  8,  42,  43,  460,  494,  495 

fish  8,  46,  47,  460,  498,  499 

Blood,  bone  and  meat 461,  496,  497 

Acid  phosphate  461,  483,  484 

Kainit    461,  488,  489 

Muriate  of  potash    8,  36,  37,  461,  488,  489 

Nitrate  of  soda 8,  13,  14,  461,  465 

Sulphate  of  potash    8,  36,  37,  461,  488,  489 

Special  mixture  No.    i    526,  527,  528,  529 

No.  2 528,  529 

Fenn's  formula  No.   i    526,  527 

No.  2 526,  527 

Special  top  dressing 528,  529 

San  Jose  scale 768 

Saperda  calcarata    336 

Candida     333 

Sawfl}'-,  peach    285,  767 

description    295 

raspberry 846 

'"Scalecide"    282 


INDEX,  931 

Page. 

Sclerotinia  Libertiana    860,  863,  868 

Screenings,  botanical  analysis  of   182 

Scurf  of  potato  357 

Selandria  obsoletum   286 

Separator  skim  milk  162 

Septoria  Kalmicola   351 

Shay,  C.  M.,  Fertilizer  Co. : — 

Shay's  Corn   fertilizer    8,  78,  79,  461,  532,  546,  547 

Grass  and  lawn  8,  78,  79,  461,  534,  535 

Potato    8,  78,  79,  461,  509,  S34>  535 

Pure  ground  bone    8,  42,  43,  461,  494,  495 

Muriate  of  potash  488,  489 

Tankage    496,  497 

Sheep  manure,  analyses  of  114,  116 

Shoemaker,  M.  L.,  &  Co. : — 

"Swift-Sure"  Guano  for  truck,  corn  and  onions  9,  82,  83,  461,  536, 

537 

Superphosphate  for  general  use  9,  58,  59,  461,  510,  511 

potatoes   ..9,  82,  83,  461,  536,  537 

Bone  meal   9,  42,  43,  461,  494,  495 

Snow-white  linden  moth  842 

Soldier  bug,  spined  769,  822 

Soluble  oils,  home-made   837 

various  kinds   840 

"Soluble  oils,"   spraying  tests  with 282 

Southern  com  root-worm  805,  8c^ 

Special  manures    74,  528 

cost  and  valuation  of  yy,  532 

guaranties  of   76,  532 

tables  of  analyses  of 78-101,  534-555 

Sphaerotheca  mors-uvae   348 

Spices  152 

Spiny  elm  caterpillar   267,  768 

Spondylocladium  abietinum   359 

atrovirens   357 

Sporotrichum  globuliferum  (entomophilum) 821 

Spray  injury  of  apple 342 

Spraying  for  the  peach  sawfly 294 

with    "soluble  oils"  282 

Squash  aphis     805,  814 

borer    805,  806 

bug    805,  81 1 

lady-beetle    , 805,  810 

Siagmo mantis  Carolina 822 

Star  feed   726,  752,  753 

Starch,  arrowroot  574 

corn  574 


932  INDEX. 

Fage. 

Starch,  potato    574 

Station,  officers  and  staff  of  iii 

Stem-rot  of  herbaceous  plants   351 

Sulphate  of  ammonia,  analysis  of 15 

Sulphuretted  hydrogen,  used  for  fumigation  275 

Sumatra  disease  of  tobacco  360 

Sunflower,  powdery  mildew  of  871 

rust  of  871 

Superphosphates,  analyses  of  nitrogenous  S6-7S,  510-529 

cost  and  valuation  of  nitrogenous  50,  501 

guaranties  of  nitrogenous  49,  501 

nitrogenous  46,  500 

Sweet  pea,  dampening  ofi  359 

Swift's  Lowell  Fertilizer  Co. : — 

Swift's    Lowell    Animal    brand    9,  66,  67,  68,  69,  461,  509,  514,  515, 

516,  517 

Bone  fertilizer  9,  98,  99,  461,  524,  525 

Dissolved  bone  and  potash  9,  70,  71,  461,  520,  521 

Empress  brand  9,  98,  99,  461,  524,  525 

Market  garden  manure  9,  60,  61,  461,  501,  512,  513 
Perfect  tobacco  grower  ...9,  104,  105,  461,  542,  543 

Potato  manure   9,  76,  96,  97,  461,  552,  553 

phosphate  9,  76,  80,  81,  92,  93,  461,  542,  543 

Special  grass  mixture  9,  82,  83,  461,  540,  541 

vegetable  manure  9,  77,  go,  91 

Ground  bone  9,  42,  43,  461,  494,  495 

Tobacco  manure   461,  538,  539 

Acid  phosphate    9,  32,  33,  461,  483,  484 

Muriate  of  potash   9,  36,  37,  461,  488,  489 

Nitrate  of  soda  9,  13,  14,  461,  465 

Dried  blood  .' 15,  466 

Tankage   44>  45,  496,  497 

Sycamore,  frost  inj  ury 360 

Syntonin,  method  of  determination  of  612 

Table  of  contents   v 

Tables  showing  results  of  fumigating  with  gases  ...274,  276,  278,  279,  281 

Tankage,  analyses  of  slaughterhouse    41,  45,  493,  497 

valuation  of    40,  493 

"Target  Brand  Scale  Destroyer"   282 

Tarred  paper  disks  835,  836 

Tartar  pomace,  analysis  of  118 

Tetranychus  bicolor    770 

Tetrastichus   xanthonielaenae    821 

Thielavia  basicola 363 

Three- Lined  leaf  beetle    844 

Thyridopteryx   ephemeraeformis    337 

Tincture  of  iodine  707 


INDEX.  933 

Page. 

Tischeria  malifoliella   267,  768 

Tobacco  beds,  methods  of  sterilizing  364 

in  1908,  root  rot  of  851 

manures  containing  potash  as  carbonate 102,  556 

guaranties    557 

tables  of  analyses  of  104,  105,  558,  559 

Tobacco,  root  rot  of  342,  363 

Tobacco  stalks,  analysis  of    117 

analyses  of  ashes  of  117 

Tobacco,  Sumatra  disease  of 360 

Tomato,  chlorosis  of   362,  857 

Treasurer,  report  of    xix,  xxi 

Trirhabda    canadensis    844 

Trumpet  creeper,  leaf  blight 362 

Uncimda  necator   855 

Uredo  aecidioides    385 

Muelleri  383,  384,  385 

Valuation  of  fertilizers   39,  491 

Vanilla  extract   158,  714 

Vegetable  potash,  analyses  of   108,  487 

Vinegar   162,  714 

Visco  Cream  713 

Water  sheds,  planting  of   244 

Weather  conditions  in  1907,  notes  on 339 

1908,  notes  on 849 

Weevil,  New  York   845 

strawberry    846 

Wheat  and  corn-cob  feeds  178,  206,  207,  727,  756,  757 

bran   170,  192-19S,  7^9,  742-745 

feed 171,  196-199,  719,  746-749 

middlings 171,  194-197,  719,  744-747 

products    170,  718 

Wheeler  Bros.  :— 

Wheeler's  Special  potato  461,  536,  537 

Ammoniated  bone  and  potash  516,  517 

Corn  special  534,  535 

White  fly,  greenhouse 806,  815 

Wilcox  Fertilizer  Co. : — 

Wilcox's   Complete  bone  superphosphate   9,  58,  59,  461,  516,  517 

Fish  and  potash  9,  64,  65,  461,  512,  513 

Grass  fertilizer   9,  82,  83,  461,  536,  537 

H.  G.  fish  and  potash  9,  56,  57,  461,  510,  511 

tobacco  special    9,  74,  78,  79,  461,  536,  537 

Potato   fertilizer     9,  86,  87,  461,  548,  549 

onion    and    vegetable    manure    9,  80,  81,  461,  536, 

537 
Special   superphosphate    9,  62,  63,  461,  520,  52: 


934  INDEX. 

Page. 
Wilcox  Fertilizer  Co.,  cont'd — 

Wilcox's  Dry  ground  fish  9,  44,  47,  461,  498,  499 

Pure  ground  bone  9,  42,  43,  461,  494,  495 

Acid  phosphate  9,  31,  32,  461,  483,  484 

Muriate  of  potash 9,  36,  37,  38,  461,  4S8,  489 

Nitrate  of  soda 9,  13,  14,  461,  465 

H.  G.  sulphate  of  potash  9,  36,  37,  488,  489 

Special  mixture  No.   i    526,  527 

No.  2  526,  527 

Willow  curculio 335 

Witch  hazel,  analysis  of 712 

Wood  ashes  m,  562 

tables  of  analyses  of  112,  113,  564,  565 

Woodruff,  S.  D.,  &  Sons  :— 

Woodruff's  Home  mixture   9,  46,  48,  56,  57,  461,  510,  511 

Muriate  of  potash   36,  37.  488,  489 

Nitrate  of  soda 13,  I4,  46S 

Acid  phosphate  483.  4^4 

Yield  tables  of  even  aged  forests  262 

Zeuzera   pyrina    847 


State  of  Connecticut 

PUBLIC  DOOUMEl^T  IsTo.  24 


Thirty-first  and  Thirty-second  Annual  Reports 

OF 

The  Connecticut  Agricultural 
Experiment  Station 

Being  the  biennial  report  for  the  two  years  ended  October  ZU 

1908 


PRINTED  BY  ORDET{  OF  THE  LEGISLATURE 


HARTFORD 

Published   by  the   State 
1908 


publication 

approved  by 

The  Board  of  Control. 


THE  TUTTLE,  MOREHOUSE  &  TAYLOR  COMPANY 


CONNECTICDT  AaRICUlTDRAL  EIPERIMEKT  STATION. 


BOARD  OF  CONTROL. 

His  Excellency,  Rollin  S.  Woodruff,  Ex  officio.  President. 

Prof.  H.  W.  Conn,  Vice  President Middletown. 

Prof.  W.  H.  Brewer,  Secretary New  Haven. 

B.  W.  Collins Meriden. 

Charles  M.  Jarvis Berlin. 

Frank  H.  Stadtmueller Elmwood. 

J.  H.  Webb Hamden. 

E.  H.  Jenkins,  Director  and  Treasurer New  Haven. 


STATION  STAFF. 

Chemists. 

Analytical  Laboratory. 

John  P.  Street,  M.S.,  Chemist  in  Charge. 

E.  Monroe  Bailey,  M.S.  C.  A.  Brautlecht,  Ph.B. 

C.  B.  Morrison,  B.S.  Clarence  W.  Rodman,  B.S. 

Laboratory  for  the  Study  of  Proteids. 
T.  B.  Osborne,  Ph.D.,  Chemist  in  Charge. 

Botanist. 
G.  P.  Clinton,  S.D. 


W.  E.  Britton,  Ph.D. 

Assistant  in  Entomology. 
B.  H.  Walden,  B.Agr. 

Forester. 
Austin  F.  Hawes,  M.F. 

Agronomist. 
Edward  M.  East,  Ph.D. 

Seed  Testing. 
Mary  H.  Jagger. 

Stenographers  and  Clerks. 

Miss  V.  E.  Cole. 

Miss  L.  M.  Brautlecht. 

Miss  E.  B.  Whittlesey. 

Miss  C.  A.  Botsford. 

In  charge  of  Buildings  and  Grounds. 
William  Veitch. 

Laboratory  Helper. 
Hugo  Lange. 

Sampling  Agent. 
V.  L.  Churchill,  New  Haven. 


TABLE  OF  CONTENTS. 


PAGE. 

Officers  and  Staff iii 

Contents  v 

Report  of  Board  of  Control ix 

Report  of  Treasurer  xix 

Corrections  and  Additions xxiii 

Report  on  Commercial  Fertilizers   i,  453 

Duties  of  Manufacturers  and  Dealers  i,  453 

Observance  of  the  Fertilizer  Law  2,  454 

Sampling  and  Collection  of  Fertilizers 10,  462 

Raw  Materials  chiefly  valuable  for  Nitrogen    13-31,  464-482 

Raw  Materials  chiefly  valuable  for  Phosphoric  Acid  ..31-34,  483-486 
Raw  Materials  of  High  Grade  containing  Potash  ...35-38,  486-491 
Raw  Materials  containing  Nitrogen  and  Phosphoric 

Acid    39-46,  491-499 

Nitrogenous  Superphosphates  and  Guanos   46-74,  500-528 

Special   Manures 74-106,  528-559 

Home  Mixtures    106-108,  559-560 

Ashes,  Cotton  Hull  and  Wood  108-114,  560-567 

Lime  and  Lime-Kiln  Ashes   114-115,  567-568 

Various  Manurial  Wastes  1 14-120,  568-570 

Report  on  Food  Products  {See  also  below,  p.  57s  et  seq.)  121 

Buckwheat  Flour  127 

Catsup  and  Chili  Sauce 129 

Chocolate  and  Cocoa   134 

Coffee    137 

Cream  of  Tartar  138 

Diabetic  Foods  138 

Honey    139 

Hygienic  Coffee   141 

Lard   143 

Lemon  Extract  144 

Maple  Syrup 150 

Olive  Oil    151 

Spices 152 

Vanilla  Extract   158 

Miscellaneous    162 

Samples  sent  by  Dairy  Commissioner 162,  713 

Summary    163,  715 

Report  on  Feeding  Stuffs  -. 165,  717 

Sampling  and  Explanations  166 

Uses  of  Analyses  168 


vi  CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

PAGE. 

Report  on  Feeding  Stuffs,  cont'd — 

Oil  Seed  Products   169-170,  717-718 

Wheat  Products   170-172,  718-720 

Corn   Products    172-174,  721-726 

Rye  Products    174,  726 

Buckwheat,  Rice  and  Miscellaneous  Products  175,  726 

Barley  Products    176-177,  726-727 

Various  Mixed  Feeds   178-179,  727-728 

Proprietary  Horse  Feeds   180,  729 

Proprietary  Dairy  and  Stock  Feeds   180,  729 

Proprietary  Poultry  Feeds  181,  731 

Miscellaneous  Feeds   183,  72,2 

Digestibility  of  Feeding  Stuffs  183,  735 

Regarding  the  Purchase  of  Feeds  185,  735 

Weight  of  One  Quart  of  Various  Feeds  189,  762 

Commercial  Feeds  containing  Weed  Seeds  72>^ 

Analyses  of  Feeds   190-209,  740-761 

Report  of  Forester  211 

Forest   Plantations    211 

Description  of  Forest  Planting  Experiments  213 

Summary  of  Results   230 

Recent  Plantations  in  Connecticut  242 

Plantations  in  State  Forests    242 

Planting  Water  Sheds   244 

Educational  Institutions   246 

Private  Plantations   248 

Older  Forest  Plantations  in  Connecticut  251 

Yield  Tables  of  Even  Aged  Forests  in  Europe 262 

Report  of  Entomologist  {See  also  below,  p.  763)   266 

Nursery  Inspection   268,  770 

Tests  of  Gases  for  Fumigating  Stock  270,  796 

Spraying  Tests  with  Soluble  Oils  282 

The  Peach  Sawfly  285 

Progress  of  Work  in  Controlling  the  Gypsy  Moth  300,  772 

The  Brown  Tail  Moth   313 

Mosquito   Studies    318,  800 

The  Chemical  Composition  of  Lead  Arsenate  and  Paris  Green         321 
Notes  on  Various  Insects   332-338,  842-848 

Report  of  Botanist  (See  also  below,  p.  850)   339,  849 

Notes  on  Fungous  Diseases 339,  849 

Root  Rot  of  Tobacco  363 

Heteroecious  Rusts  of  Connecticut  369 

Report  of  Agronomist  397 

The  Prospect  of  Better  Seed  Com  in  Connecticut 397 

Practical  Use  of  Mendelism  in  Com  Breeding 406 

Inbreeding  in  Corn    419 

Some  Essential  Points  in  Potato  Breeding  429 

Extension  Work  in  Agronomy 448 


TABLE   OF    CONTENTS.  vii 

PAGE. 

Report  on  Food  Products  {See  also  above,  p.  121)   573 

Starches    574 

Ginger    574 

Jams,  Jellies  and  Preserves 581 

Salt  586 

Infant  and  Invalid  Foods  599 

Meat  Extracts    606 

Fluid  Meat  Extracts 640 

Other  Meat  Preparations 655 

Bibliography  of  Meat  Extracts  664 

Report  on  Drugs : 

Beef,  Wine  and  Iron  673 

Headache  Preparations 686 

Ammonia  Water   704 

Tincture  of  Iodine   707 

Borax  710 

Miscellaneous  Foods  and  Drugs  711 

Foods  and  Drugs  Examined  for  the'  Dairy  Commissioner 713 

Summary    ^ 715 

Report  of  Entomologist  {See  also  above,  p.  266)  763 

Financial  Reports   y62, 

Entomological  Features  of  1908  768 

Canker  Worms  yyy 

Insects  attacking  Cucurbits   805 

Elm  Leaf  Beetle  815 

Green  Clover  Worm  828 

Treatment  of  Cabbage  Plants  to  Prevent  Injury  by  Cabbage 

Maggot   832 

Soluble  Oils,  home-made   837 

Report  of  Botanist  {See  also  above,  p.  339)   850 

Peach  Yellows  and  So-called  Yellows  872 

Chestnut  Bark  Disease   879 

Artificial  Cultures  of  Phytophthora   891 


Report  of  the  Board  of  Control 

OF    THE 

CONNECTICUT  AGRICULTURAL  EXPERIMENT 
STATION. 

To  His  Excellency,  Rollin  S.  Woodruff,  Governor  of  Connecticut: 

The  Board  of  Control  of  the  Connecticut  Agricultural  Experi- 
ment Station,  as  required  by  law,  herewith  submits  its  report  for 
the  two  years  ending  November  ist,  1908. 


Professor  Wilbur  Olin  Atwater,  of  Wesleyan  University,  died 
in  Middletown,  Conn.,  September  22d,  1907. 

The  members  of  the  Board  of  Control  of  the  Connecticut  Agricultural 
Experiment  Station,  with  this  notice  of  his  death,  desire  also  to  record 
their  appreciation  of  the  great  work  which  Professor  Atwater  did  for  the 
cause  of  Agricultural  Research,  both  in  Connecticut  and  in  the  country  at 
large.  Active  and  helpful  in  encouraging  an  interest  in  the  subject  and  in 
urging  the  estabhshment  of  an  Agricultural  Experiment  Station  in  Con- 
necticut, he  became  Director  in  the  first  Station  established  on  this  conti- 
nent, in  1875,  and  his  influence  contributed  very  largely  to  the  successful 
establishment  of  agricultural  experiment  stations  in  other  states. 

He  was  also  for  fourteen  years  Director  of  the  Storrs  Station. 

After  the  United  States  Department  of  Agriculture  had  been  created 
and  when  the  office  of  Experiment  Stations  was  organized  within  it, 
Professor  Atwater  was  appointed  its  first  director,  which  office  he  held  for 
three  years  and  did  much  in  shaping  its  policy  and  work. 

For  nearly  twenty-seven  years  and  until  his  last  illness,  he  was  a  valued 
member  of  this  Board,  contributing  to  the  management  of  its  affairs  the 
faithfulness,  experience  and  good  sense  which  had  made  him  so  success- 
ful in  his  other  work. 

Edwin  Hoyt,  a  member  of  the  Board  of  Control  of  this  Station 
continuously  since  its  incorporation  in  1877,  died  at  his  home  in 
New  Canaan,  on  April  17th,  1908. 

Born  in  1832,  educated  in  the  schools  of  his  native  town,  he  spent  a 
year  in  further  study  at  the  Potter  School,  at  Niagara  Falls,  and  a  winter 
at  the  Sheffield  Scientific  School  of  Yale  University,  and  in  1856  entered 
the  nursery  business  estabhshed  by  his  father,  and  continued  in  it  until 
his  death. 


X  CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

The  nursery  became  the  largest  in  New  England,  and  Mr.  Hoyt  became 
known  throughout  the  country  as  an  expert  nurseryman  and  orchardist. 
He  was  a  member  and  an  officer  in  the  State  Grange,  the  State  Pomo- 
logical  Society,  and  other  agricultural  organizations,  both  state  and 
national,  and  his  papers  presented  at  meetings  of  such  bodies  were  always 
concise,  convincing,  and  valued  as  the  opinion  of  a  disinterested  and 
honest  expert. 

In  his  native  town  he  was  a  prominent  worker  in  the  cause  of  temper- 
ance, a  member  of  the  Congregational  Church,  and  an  office  holder  in  it 
for  more  than  forty  years,  and  interested  in  every  movement  for  the 
advancement  of  his  town  and  the  welfare  of  its  citizens. 

He  had  represented  his  town  in  the  General  Assembly,  and  at  the  time 
of  his  death  was  President  of  the  First  National  Bank  of  New  Canaan. 

In  all  the  relations  of  life  he  showed  himself  scrupulously  honest, 
generous  and  broad-minded,  a  lover  of  righteousness  and  a  hater  of 
iniquity. 

The  members  of  this  Board  desire  to  place  on  record  their  appreciation 
of  the  long,  faithful  and  valuable  service  which  Mr.  Hoyt  rendered  to 
the  Agricultural  Station.  His  interest  in  it  and  his  services  for  it  began 
while  it  was  still  only  talked  of  as  a  possibility,  and  continued  as  long  as 
he  lived. 


The  General  Assembly,  by  joint  resohition  approved  May  ist, 
1907,  accepted  the  provisions  of  the  so-called  Adams  Act  of  the 
Congress  of  the  United  States  and  directed  that  one-half  of  the 
fund  appropriated  by  this  act  should  be  given  to  this  Station  and 
one-half  to  the  Storrs  Station. 

An  act  of  the  last  General  Assembly  concerning  Printing,  Chap- 
ter 133,  limits  the  edition  of  the  Station  report  to  12,000  copies, 
the  number  of  pages  to  400,  and  provides  that  it  shall  be  issued 
biennially.  Authority  is,  however,  given  to  the  State  Board  of 
Control  to  limit  the  number  of  copies  printed  and  to  permit  the 
printing  of  a  larger  number  of  pages  of  such  reports  as  were  made 
biennial  by  this  act.  The  Board  has  authorized  the  printing  of 
ten  thousand  copies  of  the  report,  not  to  exceed  900  pages,  at  the 
state  expense,  and  allows  it  to  be  issued  in  parts  as  the  material  is 
prepared,  so  as  to  place  the  results  of  the  work  before  the  public 
as  soon  as  they  are  ready. 

A  third  act  of  the  Assembly  affecting  this  Station  is  the  P'ood 
and  Drug  Law,  Chapter  255,  which  is  quite  like  the  National 
Law,  and  charges  this  Station  with  the  examination  of  drugs  as 
well  as  food  products,  but  makes  no  appropriation  for  the  drug 
work.  The  Station,  however,  has  been  able  to  do  something  in 
the  examination  of  druefs. 


REPORT   OF   THE   BOARD   OF    CONTROL.  XI 

Mr,  F.  H.  Stadtmueller,  of  Elmwood,  was  appointed  a  member 
of  this  Board  to  fill  the  unexpired  term  of  Mr.  Hoyt. 

On  May  ist,  1907,  Dr.  A.  L.  Winton,  chemist  in  charge  of  the 
analytical  laboratory,  after  twenty-three  years  of  most  valuable 
service  to  this  Station,  resigned  to  accept  the  position  of  chief 
of  the  United  States  Food  and  Drug  Laboratory  in  Chicago. 

On  September  ist,  1907,' Mr.  E.  J.  Shanley  resigned  his  position 
as  chemist,  to  take  a  similar  position  in  the  Chicago  Food  and 
Drug  Laboratory. 

On  October  ist,  1907,  Dr.  Kate  G.  Barber,  the  Station  micro- 
scopist,  resigned  to  take  a  similar  position  in  the  Bureau  of  Chem- 
istry of  the  United  States  Department  of  Agriculture  at 
Washington. 

Mr.  John  Phillips  Street,  a  graduate  of  Rutgers  College,  and 
for  eighteen  years  connected  with  the  New  Jersey  Station,  was 
appointed  to  succeed  Dr.  Winton,  on  May  ist,  1907. 

Mr.  C.  B.  Morrison,  a  graduate  of  the  Rhode  Island  Agricul- 
tural College,  and  employed  at  the  time  by  the  Sewage  Purification 
Department  of  the  City  of  Providence,  R.  L,  was  engaged  as 
chemist  in  September,  1907,  and  in  November,  1907,  Mr.  Harry 
R.  Stevens,  a  graduate  of  the  University  of  Vermont,  was  also 
added  to  the  staff  as  chemist,  but  was  obliged  to  resign  in  May, 
1908,  on  account  of  ill  health. 

Mr.  K.  G.  Mackenzie,  a  graduate  of  Yale  University,  also  served 
the  Station  as  chemist  for  five  months  in  1908. 

Mr.  C.  A.  Brautlecht,  a  graduate  of  the  Sheffield  School  of 
Yale  University,  was  appointed  to  the  Station  staff  as  chemist  in 
April,  1908. 

In  January,  1908,  Miss  Mary  H.  Jagger  was  employed  to 
attend  to  the  work  of  seed  testing. 

In  October  of  the  same  year  Mr.  Clarence  Rodman,  a  graduate 
of  the  University  of  Pennsylvania,  and  employed  at  the  time  as 
a  chemist  in  the  Philadelphia  Water  Works,  was  engaged  as 
chemist. 

During  the  summer  months  of  1907  and  1908,  Mr.  Paul  Graff 
was  employed  to  put  in  order  and  arrange  the  additions  to  the 
herbarium  which  are  noticed  later  in  this  report. 

Messrs.  F.  F.  Moon  and  Allen  Hodgson,  during  the  same 
time,  assisted  Mr.  Hawes  in  the  forest  survey  of  the  state. 


xii  CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

Six  hundred  and  fifty-one  analyses  of  fertilizers  were  made  in 
1907,  including  all  of  the  two  hundred  and  seventy-nine  brands 
registered  for  sale  in  the  state,  and  the  results  published  with 
appropriate  discussion  as  Part  I  of  the  biennial  report. 

In  1908  six  hundred  and  thirty-one  fertilizer  analyses  were 
made,  and  the  results  are  already  in  type. 

In  1907  fifteen  hundred  and  ninety-four  food  products  were 
examined  with  reference  to  adulteration  and  all  cases  of  adultera- 
tion reported  to  the  dairy  commissioner,  with  whom  rests  the 
enforcement  of  the  law.  A  full  report  on  all  the  samples  was 
issued  as  Part  II  of  the  report. 

In  1908  ten  hundred  and  seventy-four  analyses  of  foods,  and 
four  hundred  and  four  of  drugs  were  made  and  reported  to  the 
commissioner  as  before.  The  results  are  nearly  ready  for 
printing. 

Two  hundred  and  thirty-seven  samples  of  feeding  stuffs,  includ- 
ing nearly  if  not  quite  all  the  brands  sold  in  Connecticut,  were 
analyzed  in  1907,  and  the  results  published  and  discussed  in  Part 
III  of  the  report.  In  1908  about  the  same  number  have  been  col- 
lected and  are  now  being  examined. 

Examinations  and  analyses  have  been  made  of  all  the  brands 
of  arsenical  insecticides  which  could  be  found  in  the  state,  twenty- 
three  in  number,  and  the  results  printed  in  Bulletin  157. 

As  usual,  a  good  deal  of  miscellaneous  analytical  work  has 
been  done,  and  also  work  in  testing  and  improving  analytical 
methods. 

One  hundred  and  fifty-four  pieces  of  measuring  apparatus  for 
the  Babcock  test  have  been  tested  for  creameries  and  individuals. 
Nine  pieces  were  condemned  as  inaccurate. 

The  work  done  during  1907  and  1908  in  the  laboratory  for 
protein  research,  supported  in  part  by  the  Carnegie  Institution 
and  in  part  by  the  Adams  fund,  may  be  summarized  as  follows : 

A  full  report  on  the  Chemistry  of  Protein  of  the  Wheat 
Kernel  has  been  made  and  published  by  the  Carnegie  Institution 
as  Publication  84. 

A  new  substance,  a  dipeptide  of  proline  and  phenylalanine,  has 
been  isolated  from  one  of  the  wheat  proteins.  This  substance 
is  important,  not  only  in  connection  with  the  structure  of  wheat 
protein,  but  in  connection  with  the  chemistry  of  proteins  in 
general. 


REPORT   OF   THE   BOARD   OF    CONTROL.  Xlil 

Quantitative  determinations  have  been  made  of  the  proportions 
of  decomposition  products  yielded  by  a  considerable  number  of 
vegetable  proteins,  and  the  results  have  been  published. 

Similar  determinations  have  been  made  in  a  number  of  animal 
food  substances  to  compare  with  the  others,  and  to  determine 
whether  or  not  wide  differences  in  decomposition  products 
existed  between  animal  food  substances  similar  to  those  in 
vegetable  proteins. 

The  extended  study  of  the  determination  of  the  different  forms 
of  nitrogen  in  a  large  number  of  vegetable  and  animal  proteins 
has  been  finished. 

Experiments  with  the  nucleic  acid  of  wheat  have  settled  an 
important  point  in  the  chemistry  of  this  class  of  substances  which 
has  been  the  subject  of  much  controversy. 

The  results  of  the  work  of  this  laboratory  have  been  given  in 
twenty-one  papers  published  in  scientific  journals. 

During  1907  and  1908  the  entomological  department  has  spent 
much  effort  in  subduing  the  gipsy  moth  at  Stonington,  the  only 
place  in  the  state  where  it  has  been  found.  The  infested  area  has 
been  isolated  as  well  as  could  be  by  the  destruction  of  shrubs  and 
bushes  on  all  sides  of  it,  and  has  been  made  considerably  smaller, 
and  within  the  area  all  larvae,  pupae  and  egg  masses  discoverable 
by  men  working  from  November,  1906,  to  September,  1908,  have 
been  destroyed.  Fourteen  thousand  trees  were  banded  and 
inspected  daily  during  the  caterpillar  season  of  each  year,  and 
fifty-five  hundred  caterpillars,  two  hundred  pupae,  and  one  hun- 
dred and  forty-one  newly  laid  egg  masses  were  destroyed. 

By  act  approved  June  5th,  1907,  the  General  Assembly  of  1907 
appropriated  $1,000  for  fighting  the  gipsy  moth,  and  provided  that 
the  State  Board  of  Control  might  supply  additional  funds  to  the 
amount  of  $10,000,  if,  in  their  judgment,  it  should  be  necessary. 
Five  thousand  dollars  have  been  spent  from  this  appropriation, 
one  hundred  dollars  supplied  by  the  State  Board  of  Agriculture, 
and  $1,513.34  from  the  regular  state  appropriation  for  the 
entomologist. 

A  new  orchard  pest,  the  peach  saw-fly,  which  proved  to  be  a 
new  species,  was  studied,  and  its  life  history  determined  and 
described.  It  was  very  abundant  in  the  peach  orchards  of  one 
sections  of  the  state,  and  threatened  great  injury.  Under  the 
direction  of  the  entomologist  spraying  with  arsenate  of  lead 
controlled  the  pest  perfectly. 


xiv         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

Experiments  on  the  effectiveness  of  the  fumigation  of  nursery- 
stock  with  five  different  gases  have  been  concluded. 

Tests  of  remedies  against  the  cabbage  maggot  and  squash  borer 
have  been  completed  on  the  Station  grounds  at  Mt.  Carmel. 

Examinations  of  localities  where  mosquitoes  breed  have  been 
made,  particularly  at  Beaver  Swamp,  New  Haven,  infected  with 
the  malaria-bearing  mosquito,  and  by  request  of  health  officers, 
at  the  state  rifle  range.  East  Haven,  and  in  the  region  about 
Stamford. 

A  paper  on  the  Orthoptera  of  the  state  has  been  prepared  for 
the  Natural  History  Survey  by  Mr.  B.  H.  Walden,  and  a  gen- 
eral introduction  to  the  insects  of  the  state  by  Dr.  Britton. 

The  insect  collection  now  contains  nearly  3,500  species,  and 
over  30,000  specimens. 

Ninety-two  nurseries  and  seventy  orchards  and  gardens  have 
been  inspected,  and  338  samples  of  insects  identified  in  answer 
to  inquiries. 

Four  papers  on  entomological  subjects  have  been  prepared  for 
scientific  journals  or  reports. 

The  work  of  the  agronomist,  in  large  part  supported  by  the 
Adams  fund  for  scientific  research,  may  be  summarized  as 
follows : 

Dr.  East  has  finished  a  preliminary  study  of  the  factors 
involved  in  the  improvement  of  the  potato,  the  relation  of  physical 
and  chemical  characters  to  quality,  and  the  amount  of  fluctuation 
of  these  characters,  a  work  begun  at  the  University  of  Illinois, 
in  1 90 1,  completed  here,  oft'ered  as  a  thesis  for  the  doctorate 
degree,  and  pubHshed  by  the  Illinois  Station  as  Bulletin  127. 

A  study  of  the  physiology  of  the  production  of  seed  and  of 
the  difficulties  attending  hybridization  in  the  potato,  in  which  over 
seven  hundred  varieties  have  been  under  observation,  has  been 
finished  and  the  results  published. 

In  a  study  of  inheritance  of  fluctuations  within  a  bud  propa- 
gating line  (potatoes),  using  the  nitrogen  fluctuation  for  the 
observed  character,  the  second  generation  has  been  grown. 

The  crosses  between  varieties  of  potatoes  made  in  1907  were 
grown  in  1908,  in  order  to  study  the  inheritance  of  different  unit 
characters. 

In  a  study  of  the  graft  hybrids  in  potatoes  it  has  been  shown 
that  no  transference  of  coloring  matter  can  be  made,  and  cer- 
tain errors  in  published  work  on  the  subject  have  been  explained. 


REPORT   OF   THE   BOARD   OF    CONTROL.  XV 

Some  interesting  results  on  bud  variation  have  been  obtained 
which  offered  a  new  explanation  for  the  phenomenon. 

The  experiment  at  Elmwood  in  increasing  by  selection  the  pro- 
tein content  of  a  variety  of  corn  has  been  continued.  At  the 
station  at  Granby  several  hundred  crosses  of  corn  have  been  made 
to  determine  the  inheritance  of  various  characters,  and  the  second 
generation  of  several  previous  crosses  have  been  grown,  as  well 
as  the  third  generation  of  certain  inbred  varieties. 

The  cooperative  tests  in  corn  breeding,  started  in  I905»  have, 
in  1908,  been  left  entirely  to  the  cooperators. 

In  studying  the  laws  of  inheritance  with  tobacco,  which  is  a 
plant  better  suited  to  the  purpose  than  any  other  of  economic 
value  grown  here,  125  varieties  have  been  grown  for  classifica- 
tion, for  observation  as  to  commercially  desirable  kinds,  and, 
chiefly,  to  obtain  varieties  with  different  unit  characters  to  use  in 
heredity  experiments. 

In  the  greenhouse  an  experiment  with  tomatoes  is  in  progress 
to  determine  whether  it  is  possible  by  abnormal  treatment  of  the 
developing  seed  to  change  in  any  way  the  usual  characters  of 
the  offspring.     The  question  is  one  of  great  economic  importance. 

Field,  laboratory,  and  pot  experiments  have  been  made  to  test 
the  availability  of  potassium  in  fine  ground  feldspar,  so  far 
without  decisive  results. 

On  the  Station  farm  land  the  study  of  soil  needs  and  improve- 
ment by  rotations,  cover  crops,  green  manures  and  fertilizers  has 
been  continued  with  observations  on  fall  and  spring  seeding  with 
clover,  together  with  experiments  in  spraying  and  other  means 
of  combating  insect  and  fungus  attacks ;  the  latter  under  the 
direction  of  the  entomologist  and  botanist. 

Four  papers  on  the  subject  of  Dr.  East's  work  have  been  read  at 
meetings  of  specialists  or  published  in  scientific  journals. 

The  botanist,  Dr.  Clinton,  was  absent  on  leave  for  two  months 
in  1908,  to  do  some  preliminary  work  on  the  inoculation  of  the 
brown  tail  moth  with  the  Empusa  disease  for  the  State  of  Massa- 
chusetts. This  was  done  at  Harvard  University  under  the  direc- 
tion of  Prof.  Thaxter,  formerly  botanist  of  this  Station. 

Besides  study  and  observation  on  the  fungous  troubles  of  crops 
in  all  parts  of  the  state,  collecting  and  arranging  additions  to 
the  herbarium,  and  conducting  experiments  on  the  Station  experi- 


Xvi         CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

ment  land  and  in  the  greenhouse,  the  study  of  the  botanist  dur- 
ing the  last  two  years  has  been  chiefly  on  the  following  subjects  : 

1.  The  "Calico"  disease  of  tobacco  and  chlorosis  in  other 
plants. 

2.  The  downy  mildew  of  Connecticut.  (For  the  State  Nat- 
ural History  Survey  of  the  state.) 

3.  A  study  of  100  varieties  of  muskmelons,  especially  regard- 
ing their  resistance  to  blight  and  adaptability  to  Connecticut 
conditions. 

4.  The  root  rot  of  tobacco. 

5.  Certain  Peridermia  and  their  telial  stage. 

6.  Potato  blight. 

On  the  Station's  experimental  forest  the  forester  has  con- 
tinued experiments  on  the  economic  planting  of  white  pine,  and 
on  different  methods  of  seeding  and  planting  forest  trees,  on 
fertilizing  young  trees  by  growing  cow  peas,  on  the  progress  of 
the  white  pine  disease,  and  the  best  treatment  of  the  pine  weevil. 

The  forest  nursery  contains  about  950,000  seedling  trees,  mostly 
one-year-olds,  and  300,000  seedlings  in  addition  have  been  sold 
at  cost  to  landowners. 

Four  acres  of  pine  growth  30  years  old  have  been  bought  in 
Enfield  for  experiments  in  thinning. 

The  increased  interest  in  forest  planting  is  shown  by  the  facts 
that  about  100,000  forest  trees  were  planted  in  the  state  in  1906, 
350,000  in  1907,  and  600,000  in  the  present  year. 

A  number  of  landowners  in  marketing  their  mature  lumber 
are  doing  the  work  by  improvement  thinnings  planned  by  the 
Station  forester. 

As  state  forester,  Mr.  Hawes  has  carried  on  improvement  thin- 
ning and  planting  work  both  at  the  Portland  and  Union  forests. 
A  tract  of  130  acres  of  waste  land  frequently  burned  over  has 
been  bought  for  a  state  forest  in  Simsbury,  and  20,000  trees 
already  planted. 

The  fire  warden  service  has  been  greatly  improved  and  a  pam- 
phlet of  instructions  to  fire  wardens,  containing  also  a  list  of 
wardens  with  telephone  calls  of  those  who  have  them,  has  been 
distributed. 

In  1908,  alone,  the  wardens  reported  156  fires,  burning  over 
10,807  acres,  of  which  6,100  were  sprout  and  timber  land.     568 


REPORT   OF   THE    BOARD   OF    CONTROL.  XVll 

cords  of  cut  wood  were  destroyed.  i,347  men  were  employed 
in  fighting  fire,  and  the  total  amount  paid  them  by  state,  county, 
and  town  was  about  $9.00  per  fire. 

In  Simsbury,  alone,  a  single  patrol  during  the  danger  season 
of  April  and  May  put  out  35  fires  before  any  considerable  damage 
was  done. 

A  forest  survey  has  been  made  of  Litchfield  and  Fairfield 
counties,  and  in  cooperation  with  the  Yale  Forest  School  of  New 
Haven  County,  estimating  the  quantity  and  kind  of  the  standing 
timber.  All  wood  lots  of  over  ten  acres  are  plotted  on  topo- 
graphic sheets.  The  map  is  completed  and  the  report  prepared 
on  the  wood  supplies  and  wood  industries  of  these  counties. 

Miss  Jagger  has  made  five  hundred  and  thirty-five  examina- 
tions of  seeds,  a  part  on  samples  sent  by  seedsmen  and  buyers, 
and  a  part  bought  by  our  sampling  agent  in  different  parts  of 
the  state. 

Twenty-eight  thoroughbred  Guernsey  cows  and  twenty-nine 
Jerseys  have  been  tested  for  advanced  registry  by  monthly  deter- 
minations of  production  of  milk  and  of  butter-fat.  The  tests  of 
twelve  Guernseys  and  ten  Jerseys  have  been  finished,  and  eleven 
were  withdrawn  before  the  year's  test  was  finished. 

At  present  seventeen  Guernseys  and  eighteen  Jerseys  are  being 
tested. 

Within  the  period  covered  by  this  report  the  Station  has 
acquired  by  purchase  for  its  collections  several  hundred  species 
of  European  fungi,  and  the  herbarium  of  J.  N.  Bishop,  of  Plain- 
ville,  containing  between  two  and  three  thousand  specimens. 

Dr.  W.  A.  Murrill,  of  the  New  York  Botanical  Garden,  has 
given  the  Station  one  hundred  specimens  of  the  common  Poly- 
porei. 

Mr.  James  Shepard,  of  New  Britain,  has  given  the  Station  the 
herbarium  of  his  daughter,  recently  deceased.  Miss  Celia  Antoi- 
nette Shepard,  containing  one  thousand  or  more  species,  chiefly 
from  Connecticut,  but  including  many  from  other  states  and 
foreign  countries. 

Prof.  S.  W.  Johnson,  formerly  director  of  this  Station,  has 
given,  conditionally,  to  its  library  five  hundred  bound  volumes 
and  many  pamphlets  from  his  valuable  agricultural  library. 
These  include  sets  of  a  number  of  valuable  journals,  almost 
impossible  to  get  now  from  book  dealers,  and  works  on  scientific 


Xviii     CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

agriculture  which  represent  its  history  and  development  from 
the  early  years  of  the  last  century. 

Members  of  the  staff  have  made  addresses  at  one  hundred  and 
six  institutes,  grange  meetings,  and  other  agricultural  gatherings. 

The  Station  has  cooperated  with  the  United  States  Department 
of  Agriculture  in  tobacco  breeding  work  and  in  a  study  of  the 
improvement  of  sweet  corn  by  selection  of  seed. 

In  the  two  years  the  Station  has  published  one  report  of  four 
hundred  and  twenty-three  pages,  with  thirty-three  plates,  and  one- 
half  its  biennial  report  of  four  hundred  and  fifty-three  pages, 
with  forty-seven  plates.  It  has  also  issued  six  bulletins  aggre- 
gating one  hundred  and  forty-one  pages,  with  nine  plates  and 
figures,  and  four  bulletins  of  immediate  information,  aggregating 
twenty-three  pages  and  nine  figures.  The  editions  range  from 
eight  thousand  to  ten  thousand  copies. 

In  the  two  years  fourteen  thousand  three  hundred  and  forty- 
two  letters  and  manuscript  reports  have  been  written  and  mailed 
from  the  Station. 

All  of  which  is  respectfully  submitted. 

(Signed)  William  H.  Brewer,  Secretary. 

New  Haven,  Conn.,  November  i,  igo8. 


REPORT  OF  THE  TREASURER,  1907 


E.  H.  Jenkins,  in  account  with  The  Connecticut  Agricultural  Experi- 
ment Station  for  the  fiscal  year  ending  September  30,  1907. 

Receipts. 
Balance  on  hand,  October  i,  1906 : 

Analysis   Fees    $522.15 

Insect  Pest  Appropriation  650.00 

$1,172.15 

State  Appropriation,  Agriculture    $10,000.00 

State  Appropriation,  Food    2,500.00 

State  Appropriation,  Insect  Pest    3,000.00 

State  Appropriation,  Gypsy  Moth 2,500.00 

United  States  Appropriation,  Hatch    7)5oo.oo 

United  States  Appropriation,  Adams    3,750-00 

Analysis  Fees   2,900.00 

Miscellaneous   Receipts    46-45 

From  the  Lockwood  Estate  10,800.00 

42,996.45 

Total    $44,168.60 

Disbursements. 

E.  H.  Jenkins,  Salary  $2,800.00 

W.  H.  Brewer;       "        100.00 

V.  E.  Cole,             "       800.00 

L.  M.  Brautlecht,  "       600.00 

A.  L.  Winton,         "       1,458-33 

J.  P.  Street,            "       1,041.67 

T.  B.  Osborne,       "        2,200.00 

E.  M.  Bailey,         "        1,350.00 

Kate  Barber,           "        1,066.66 

E.  J.  Shanley,         "        991.66 

C.   B.   Morrison,     "        18.75 

W.  E.  Britton,       "        1,700.00 

G.    P.    Clinton,       "        2,000.00 

A.  F.  Hawes,         "       1,291.66 

E.  M.  East,            "       1,700.00 

J.  B.  Olcott,            "       375-00 

H.  Lange,                "       866.67 

V.  L.  Churchill,     "        760.00 

William   Veitch,      "        633.33 

T.  E.  Keitt,            "       60.00 

W.  Drushel,            "       150.00 

R.  W.  Langley,       "        358.90    ^ 

Labor  3,366.21 

Publications    583.29 


XX  CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

Postage    $    160.45 

Stationery   283.94 

Telephone  and  Telegraph  211.65 

Freight  and  Express 149.98 

Gas  and  Kerosene  32921 

Coal    1,302.05 

Water    157-39 

Chemicals  and  Laboratory  Supplies   i, 194-35 

Agricultural  and  Horticultural  Supplies   33i-i7 

Miscellaneous   Supplies    250.26 

Botanical  Supplies 72-20 

Fertilizers    255.29 

Feeding  Stuffs    118.53 

Library  and  Periodicals  594-68 

Tools  and  Machinery  300-74 

Furniture  and  Fixtures   137-40 

Scientific  Apparatus    82.33 

Traveling  by  the  Board    79-40 

Traveling  by  the  Staff     623.19 

Traveling  in  connection  with  Adams'  Fund   Investi- 
gations      178.76 

Tobacco  Experiment 75-30 

Fertilizer    Sampling    206.27 

Food  Sampling  34i-2i 

Insurance    28.20 

Insect  Pest  Appropriation  to  State  Entomologist 3,650.00 

Contingent    193-45 

Forestry  and  Lockwood  Expenses   2,256.85 

Gypsy  Moth  Appropriation  to  State  Entomologist  . . .  2,500.00 

New  Buildings    88.12 

Betterments    ii5-27 

Repairs    698.22 

Rental  of  Land   120.00 


Balance  on  hand,  October  i,  1907: 

Analysis   Fees    $307-79 

State  Agricultural  Appropriation   502.82 


$43,357-99 


810.61 


Total $44,168.60 

New  Haven,  Conn.,  November  5,  1907. 
This  Certifies  that  we  have  examined  the  accounts  of  E.  H.  Jenkins, 
Treasurer  of  The  Connecticut  Agricultural  Experiment  Station,  for  the 
year  ending  September  30,  1907,  compared  the  same  with  the  vouchers 
therefor  and  found  them  correct. 

William   P.  Bailey, 
Edward  S.  Roberts, 

Auditors  of  Public  Accounts. 


REPORT  OF  THE  TREASURER,  1908 


E.  H.  Jenkins,  in  account  with  The  Connecticut  Agricultural  Experi- 
ment Station  for  the  fiscal  year  ending  September  30,  1908. 

Receipts. 
Balance  on  hand,  October  i,  1907 : 

Analysis   Fees .' . .     $307.79 

State  Agricultural  Appropriation   502.82 

$810.61 

State  Appropriation,  Agriculture    $10,000.00 

State  Appropriation,  Food    2,500.00 

State  Appropriation,  Insect  Pest    3,000.00 

State  Appropriation,  Gypsy  Moth    2,500.00 

United  States  Appropriation,  Hatch   7,500.00 

United  States  Appropriation,  Adams     4,750.00 

Analysis  Fees    8,799.98 

Sale  of  Tobacco    65.97 

Sale  of  Farm  Products     228.25 

Miscellaneous   Receipts    433-52 

From  the  Lockwood  Estate 9,177.40 

48,955-12 

Total    $49,765.73 

Disbursements. 

E.  H.  Jenkins,   Salary  $2,800.00 

W.  H.  Brewer,       "       100.00 

V.  E.   Cole,             "       850.00 

L.  M.  Brautlecht,  "        650.00 

J.  P.  Street,           "        2,500.00 

T.  B.  Osborne,       "        2,200.00 

E.  M.  Bailey,          "        1,550.00 

C.  B.   Morrison,     "        925.00 

H.  R.  Stevens,       "       500.00 

K.  G.  Mackenzie,  "       363.50 

C.  A.  Brautlecht,  " 450.00 

R.  S.  Graves,         "       70.00 

W.  E.  Britton,        "       2,000.00 

G.  P.  Clinton,         "        1,833.32 

A.  F.  Hawes,          "       » . . .  1,800.00 

E.  M.  East,            "       1,900.00 

J.  B.   Olcott,           "       200.00 

H.  Lange,                "       925.00 

V.  L.  Churchill,     "        825.00 

William   Veitch,      '"        675.00 

H.  W.  Kiley  (Labor)    728.00 

Wm.    Pokrob,        "          728.00 

C.  D.  Hubbell,      "         728.00 


xxii       CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

M.  Howley  (Labor)    $   280.00 

Labor   2,426.42 

Publications    i,445-i7 

Postage    229.91 

Stationery    210.79 

Telephone  and  Telegraph  144.92 

Freight  and  Express 128.49 

Gas  and  Kerosene  428.36 

Coal    1,469.00 

Water    189.96 

Chemicals  and  Laboratory  Supplies    1,283.56 

Agricultural  and  Horticultural  Supplies   209.91 

Miscellaneous   Supplies   164.42 

Botanical   Supplies   i5-00 

Fertilizers    241.14 

Feeding  Stuffs    102.53 

Library  and   Periodicals    612.28 

Tools  and  Machinery  75.85 

Furniture  and  Fixtures   462.63 

Scientific  Apparatus    85.47 

Traveling  by  the  Board  53.28 

Traveling  by  the  Staff     1,149.18 

Traveling  in   connection  with  Adams   Fund   Investi- 
gations      19380 

Tobacco   Experiment    1,272.47 

Fertilizer  Sampling  164.10 

Food   Sampling  229.83 

Insurance    275.25 

Insect  Pest  Appropriation  to  State  Entomologist  ....  3,000.00 

Contingent    1 19.50 

Forestry  and  Lockwood  Expenses  1,899.88 

Gypsy  Moth  Appropriation  to  State  Entomologist  . . .  2,500.00 

Betterments    795-51                 i 

Repairs    1,412.90 

Grounds     200.00 

Rental  of  Land 130.00 

$48,902.33 

Analysis  Fees  on  hand,  Sept.  30,  1908  863.40 


Total $49,765-73 

New  Haven,  Conn.,  October  14,  1908. 
This  Certifies  that  we  have  examined  the  accounts  of  E.  H.  Jenkins, 
Treasurer  of  The  Connecticut  Agricultural  Experiment  Station,   for  the 
year    ending    September    30,    1908,    have    compared    the    same    with    the 
vouchers  therefor  and  found  them  correct. 

William  P.  Bailey, 
Edward  S.  Roberts, 

Auditors  of  Public  Accounts. 


CORRECTIONS  AND  ADDITIONS. 


Bulletin  163,  page  13.  Second  paragraph  from  bottom.  The  Stearns 
Lime  Co.  offer  water-slaked  lime  at  $5.00  in  bulk,  $6.00  in  bags, 
and  delivered  about  $7.25.  This  makes  the  cost  of  pure  lime  and 
magnesia  60  cents  per  100  pounds,  instead  of  73,  as  given  in  the 
Bulletin. 

Report,  page  4,  twentieth  line,  strike  out  "Wheeler's  Havana  Tobacco 
Grower." 

page  II,  sixteenth  line  from  the  bottom,  for  652  read  651. 
pages  56,  60,  74.  The  fertilizer  bearing  the  name  of  E.  B.  Clark 
Co.,  Milford,  Conn.,  is  made  by  that  firm  at  its  works  at 
Communipaw,  N.  J.  On  pages  56,  60  and  74  of  the  Report  it  is 
stated  that  the  fertilizer  is  "made  for"  E.  B.  Clark  Co.  This  is 
an  error. 

pages  56  and  57.  The  price  of  Olds  and  Whipple's  Home  Mixture 
is  $38.00  per  ton,  instead  of  $28.00,  as  given  in  the  table.  The 
percentage  difference  is  13. i. 

page  115.  Lime-Kiln  Ashes,  last  line,  under  18944,  for  "103"  read 
54;   for  "loi"  read  39. 

page  119.  The  statement  that  the  L  M.  P.  Plant  Food  contains 
essentially  55  per  cent,  of  nitrate  of  potash  and  45  per  cent,  of 
phosphate  of  soda  is  incorrect.  It  consists  essentially  of  phos- 
phate and  nitrates  of  the  alkalies.  A  more  particular  statement  is 
not  justified  by  the  figures. 

page  271,  second  line  from  top,  for  "weight"  read  weigh, 
page  510.     The  cost  price  of  Manchester's  Formula,  No.  20767,  is 
$30.00  per  ton,  instead  of  $32.00,  and  the  percentage  difference  4.4, 
instead  of  11.3. 

page  528,  last  line  of  table,  the  dealer's  price  is  $45.00  and  the 
calculated  valuation  $34.56. 
page  534,  note,  read  530  instead  of  529. 

page  725,  last  paragraph.  The  Hominy  Feed  sold  by  M.  F.  Bar- 
ringer,  Philadelphia,  was  shipped  with  a  guaranty  of  composition, 
as  required  by  law. 

page  727,  second  paragraph.  After  One  ex,  strike  out  Ai.  The 
manufacturer  states  that  the  One  ex  is  the  lowest  grade  of 
distillers'  grains  and  the  mark  Ai  had  never  been  used  in  connec- 
tion with  it. 

The  feed  represented  by  sample  20710  was  not  made  by  the  Biles 
Co. 

To  the  explanation  regarding  Dried  Distillery  Grains  on  pages  176 
and  726  may  be  added  the  following  note  regarding  the  several 
kinds  of  distillery  grains  sold  by  the  J.  W.  Biles  Co. : 


xxiv     CONNECTICUT  EXPERIMENT  STATION  REPORT,   I907-I908. 

Four  ex  is  the  product  of  alcohol  distilleries,  consisting  of  88  to 
90  per  cent,  of  corn  residues  with  10  to  12  per  cent,  of  "small 
grains,"  chiefly  malted  barley,  with  a  few  oats  coming  as  an 
unavoidable  mixture  in  the  barley. 

Two  ex,  the  product  of  Bourbon  whiskey  distilleries,  contains  60 
to  80  per  cent,  of  corn  residues  and  20  to  40  per  cent,  residues  of 
"small  grains,"  chiefly  rye  and  malted  barley,  with  a  few  oats. 

Rye  grains,  the  product  of  rye  whiskey  distilleries,  may 
consist  wholly  of  rye  residues,  or  of  rye  and  malted  barley,  with 
a  few  oats,  or  they  may  have  a  large  admixture  of  corn. 

One  ex  grains  are  from  vinegar  and  yeast  factories,  containing 
about  50  to  60  per  cent,  of  com  residues  and  40  to  50  per  cent,  of 
"small  grains." 

page  729,  after  the  words,  "Biles'  Union  Grains  contain,"  insert 
cotton  seed  meal.  The  manufacturers  state  that  the  oat  product 
is  very  small  in  quantity  and  comes  entirely  from  the  oats  which 
all  malted  barley  contains  as  an  accidental  mixture,  the  ingredients 
of  the  mixture  being  distillery  grains,  linseed  and  cotton  seed 
meal,  hominy  feed,  wheat  middlings  and  bran  and  barley  malt 
sprouts, 
page  yyy,  last  line,  for  "Ridley"  read  Riley. 


State  of  Connecticut 


REPORT 


OF 


The  Connecticut  Agricultural 
Experiment  Station 

REPORT  OF  THE  STATION  BOTANIST,  1909-1910 

G.  P.  CLINTON,  Sc.D. 

toNG  PART  X  OF  THE  BIENNIAL  REPORT  OF  1909-1910 


CONNECTICUT 

AGRICULTURAL  EXPERIMENT 
STATION 


REPORT  OF  THE  BOTANIST 

1909  and  1910 
G.  P.  CLINTON,  ScD. 


PAGE 

I.  Notes  on  Plant  Diseases  of  Connecticut, 713 

A.  Diseases  in  Relation  to  Weather  in  1909  and  1910,     .     .     .  713 

B.  New  Observations  on  Diseases  Previously  Reported,       .     .  716 

C.  Diseases  or  Hosts  Not  Previously  Reported, 723 

II.  Spraying  Potatoes  in  Dry  Seasons, 739 

III.   Oospores  of  Potato  Blight,  Phytophthora  infestans, 753 


ISSUED  JUNE,  1911 


PART  X. 
REPORT  OF  THE  BOTANIST  FOR  1909  AND  I9I0. 

G.  P.  Clinton,  Sc.D. 


I.     NOTES  ON  PLANT  DISEASES  OF  CONNECTICUT. 

A.      DISEASES  IN  RELATION  TO  WEATHER  IN   I909  AND   I9IO. 

Weather  Conditions  in  ipop.  The  winter  of  1908-09  was 
not  especially  severe,  so  that  trees  did  not  show  any  unusual 
injury,  except  from  a  couple  of  ice  storms  in  February,  1909. 
These  storms  so  heavily  coated  the  limbs  that  considerable 
damage  resulted,  especially  to  shade  and  forest  trees  in  the 
northern  half  of  the  state,  where  the  storm  was  more  severe. 
The  spring  of  1909  was  rather  wet  and  backward,  so  that  such 
fungous  troubles  as  peach  leaf  curl,  apple  scab,  etc.,  that  gain 
their  foothold  at  this  time  of  the  year,  were  unusually  prominent. 

The  summer,  however,  especially  in  July  and  August,  like 
the  two  preceding  seasons,  was  one  of  drought,  but  it  was 
broken  in  August  by  rains  that  prevented  serious  damage  to 
rriost  of  the  crops.  The  late  fall  proved  to  be  very  dry.  The 
first  killing  frost  did  not  occur  until  October  13. 

Diseases  Prevalent  in  ipop.  The  following  troubles  were 
conspicuous  or  unusually  injurious  during  this  season.  Apple: 
Black  Rot  (Leaf  Spot  form).  Rust,  Scab,  and  Spray  Injury 
(Bordeaux).  Ash:  Rust.  Chestnut:  Bark  Disease.  Egg 
Plant:  Wilt  (Fusarium?).  £/w;  Leaf  Spot.  Muskmelon: 
Leaf  Mold,  Anthracnose.  Peach:  Brown  Rot  (spring  form  on 
twigs,  etc.).  Leaf  Curl.  Plum:  Black  Knot.  Potatoes:  Tip 
Burn,  Scab.  Quince:  Leaf  Blight.  Rose:  Rust.  Spinach: 
Leaf  Mold.  Strawberries:  Powdery  Mildew,  Winter  Injury 
(root  killing).     Tobacco:   Calico. 

Of  the  above  diseases  the  leaf  spot  of  elm,  which  was  quite 
serious  in  some  places,  is  discussed  later  in  this  Report  (p.  717). 
50 


714    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

The  winter  seemed  in  some  way  to  have  weakened  the  spinach 
crop  in  the  vicinity  of  Greens  Farms,  for  there  were  reports 
that  several  of  the  crops  there  failed  because  of  the  subsequent 
action  of  the  leaf  mold  fungus  described  in  the  Report  for  1905, 
page  275.  Mr.  Joseph  Adams,  writing  of  this  trouble,  said:  "1 
have  a  patch  of  spinach  (sown  last  September  in  connection  with 
Mr.  L.  P.  Wakeman),  which  is  practically  worthless  from  a  black 
spot  which  covers  the  leaves.  This  is  the  worst  I  ever  saw.  This 
piece  contains  about  an  acre,  and  we  have  another  piece  that  is 
not  quite  as  bad."  This  fungus  was  identified  by  us  previously  as 
Heterosporium  variable  Cke.,  and  Professor  Thaxter,  who 
examined  these  later  specimens,  writes  that  it  was  also  described 
by  Cooke  as  Cladosporium  subnodosum  (see  Grev.  17:  67.   1889). 

Specimens  of  strawberry  plants  were  received  about  the 
middle  of  June,  both  from  Essex  and  Naugatuck,  with  complaints 
that  some  trouble  was  killing  off  certain  fields  in  those  places. 
Examination  revealed  no  fungus  or  insect  as  responsible,  but 
showed  that  the  rootlets  were  dead,  while  the  crowns  were 
still  alive.  This  was  a  trouble  similar  to  that  seen  once  before, 
and  discussed  in  the  Report  for  1905,  page  276.  Apparently 
there  was  enough  life  and  food  in  the  crowns  to  put  forth 
leaves  in  the  spring,  but  with  the  approach  of  warm  weather 
these  suddenly  died  off  from  lack  of  moisture,  etc.  The  trouble 
seems  to  be  due  to  winter  injury  of  the  roots,  which  had  either 
suffered  from  drought  the  previous  year  or  else  had  not  been 
properly  protected  by  snow  or  mulch  during  the  winter. 

Weather  Conditions  in  ipio.  The  winter  of  1909-10  was 
not  especially  severe  on  the  whole,  though  one  or  two  quite 
cold  spells  were  recorded  in  .  January.  March  proved  to  be 
unusually  warm  and  open,  and  the  spring  started  early,  but 
afterwards  cool,  rainy  weather  in  May  kept  back  the  vegetation 
so  that,  as  in  the  preceding  spring,  it  was  somewhat  backward, 
and  developed  an  unusual  amount  of  spring  fungous  troubles. 
There  were  two  very  late  frosts,  in  May  and  early  June,  that 
did  more  or  less  injury  to  fruit  blossoms  in  certain  parts  of 
the  state,  especially  cherries,  apples  and  strawberries,  and  also 
killed  or  injured  the  foliage  on  certain  shrubs,  etc.,  especially 
in  low  places.  At  Windsor  we  saw  small  scrub  oaks  whose 
leaves  were  all  killed  as  if  by  fire.  Some  injury  to  coniferous 
plants  was  also  observed,  and  no  doubt  much  of  the  russeting 


NOTES    ON    PLANT   DISEASES    OF    CONNECTICUT.  7^5 

of  apples,  so  common  this  year,  was  traceable  in  part  to  these 
frosts. 

Again  the  summer  proved  to  be  one  of  drought,  thus  making 
four  years  in  succession  that  may  be  so  classed.  However,  like 
the  preceding  one,  it  was  temporarily  broken  in  midsummer  by 
rains  that  saved  most  of  the  crops  from  serious  injury,  though 
potatoes,  especially  early  varieties,  were  a  very  light  crop.  The 
fall  months  were  unusually  dry,  and  this  late  drought  was  not 
broken  until  late  in  December,  so  that  a  water  famine  threatened 
many  communities.  As  in  the  preceding  year,  the  first  fall 
frost  was  delayed  until  the  middle  of  October,  thus  favoring 
the  late  crops. 

Diseases  Prevalent  in  ipio.  Among  the  most  conspicuous 
diseases  of  the  year  may  be  mentioned  the  following.  Apple: 
Rust,  Scab,  Frost  and  Spray  Injury.  Cherry  and  Plum:  Black 
Knot.  Chestnut:  Bark  Disease,  Drought  Injury.  Corn:  Smut. 
Hollyhock:  Rust.  Maple:  Leaf  Scorch.  Muskmelon:  Mildew 
Blight.  Peach:  Leaf  Curl,  Brown  Rot  (chiefly  spring  infection 
of  twigs,  etc.).  Pear:  Scab.  Pines:  Pine-Sweetfern  Rust. 
Potatoes:  Rot  (Blight),  Tip  Burn.  Rye  and  Barley:  Powdery 
Mildew.     Quince:    Rust.     Sycamore:    Anthracnose. 

Concerning  the  spray  and  frost  injury  of  apples,  there 
appears  a  discussion  in  Part  VII  of  this  Report.  There  was 
more  peach  leaf  curl  than  we  have  seen  before  in  this  state, 
and  while  the  wet  spring  favored  twig  infection  with  brown 
rot,  this  did  little  harm  to  the  mature  fruit  except  during  a  wet 
week  in  September,  when  some  injury  was  done  to  certain 
varieties  in  the  vicinity  of  Wallingford.  Potatoes  suffered 
most  from  tip  burn,  but  the  rains  came  so  that  blight  developed 
slightly  on  the  late  varieties  and  caused  some  rot  of  the  tubers 
for  the  first  time  in  several  years.  Blight,  in  late  August  and 
early  September,  carried  off  many  of  the  melon  fields  that  had 
not  been  sprayed. 

The  effect  of  successive  droughts  of  the  past  four  years  has 
begun  to  be  manifest  on  our  shade  and  forest  trees,  so  that  an 
unusually  large  number  of  them  are  dying.  This  is  especially  true 
of  the  chestnuts,  where  the  blight  fungus  plays  a  very  important 
part  on  these  weakened  trees. 

On  the  whole,  1909  and  19 10,  because  of  their  dry  summers, 
were  not  years  in  which  fungi  became  especially  troublesome, 


7l6    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I9O9-I9IO. 

except  those  starting  during  the  wet  springs.  In  Parts  B  and  C 
of  this  paper  we  discuss  certain  diseases  that  are  new  to  the 
state,  or  concerning  which  special  information  was  obtained. 

B.       NEW  OBSERVATIONS  ON  DISEASES  PREVIOUSLY  REPORTED. 

APPLE,  Pyrus  Mains. 

Spray  Injury.  Both  during  1909  and  19 10  there  was  con- 
siderable injury  resulting  from  spraying  apples  in  this  state 
with  Bordeaux  mixture.  As  previously  reported,  this  injury 
was  of  the  nature  of  leaf  spotting  and  fruit  russeting.  Experi- 
ments conducted  in  19 10  with  different  fungicides  to  replace 
Bordeaux,  because  of  this  tendency  to  injure,  showed  that  there 
was  danger  of  serious  leaf  spotting  and  subsequent  fall  with 
"One  for  All"  (rate  5  or  6  lbs.  to  50  gallons  of  v/ater),  and 
also  with  "Sulfocide"  (rate  i  to  200)  when  either  Paris  green 
or  arsenate  of  lead  was  used  with  it,  though  the  injury  with 
Paris  green  when  lime  was  added  was  lessened.  Even  without 
these  insecticides,  this  strength  of  "Sulfocide"  sometimes  pro- 
duces more  or  less  leaf  spotting.  Some  leaf  injury  was  also 
caused  by  Bogart's  "Sulphur  Compound"  used  at  the  rate 
of  i^  to  50.  Practically  no  russeting  or  leaf  spotting  was 
produced  by  any  of  the  straight  commercial  lime-sulphur 
sprays,  with  arsenate  of  lead  added,  even  at  the  rate  of  i^^  to 
50,  except  what  occasionally  occurred  in  the  shape  of  sun 
scald  on  the  most  exposed  side  of  the  fruit.  While  this  rarely 
occurred,  when  it  did  it  produced  rather  serious  injury.  On 
the  whole,  the  straight  commercial  lime-sulphur  sprays  were 
the  most  satisfactory  as  regards  least  spray  injury.  For  further 
information,  see  Part  VII  of  this  Report. 

CHESTITUT,  Castanea  dentata. 

Chestnut  Bark  Disease,  Diaporthe  parasitica  Murr.  In 
our  Report  for  1908,  page  879,  we  gave  an  account  of  this 
trouble.  At  that  time  it  had  been  reported  in  every  one  of 
the  twenty-three  towns  of  Fairfield  County,  and  in  eight  towns 
in  New  Haven  County,  making  thirty-one  towns  altogether. 
At  the  time  of  writing  this  article  (March  20,  191 1),  its  known 
distribution  is  as  follows :  Fairfield  County,  twenty-three  towns ; 
New    Haven    County,    twenty-one    towns;     Litchfield    County, 


NOTES   ON    PLANT  DISEASES   OF   CONNECTICUT.  7^7 

fourteen  towns;  Hartford  County,  seven  towns;  Middlesex 
County,  two  towns;  Tolland  County,  three  towns;  Windham 
County,  one  town;  New  London  County,  one  town.  This 
makes  a  total  of  seventy-two  towns,  of  which  only  seven  are 
east  of  the  Connecticut  River,  We  have  no  doubt  that  a  more 
thorough  survey  of  that  region  would  reveal  its  presence,  in 
an  inconspicuous  way,  in  quite  a  few  more  towns. 

This  increased  distribution  in  the  last  three  years  may  indicate 
that  the  disease  has  spread  to  those  new  localities,  or  it  may 
mean  that  a  more  thorough  search  has  revealed  its  presence, 
and  that  it  has  also  become  more  prominent  because  of  the 
four  years  of  drought  that  have  occurred,  beginning  with  1907. 
There  are  those  who  believe,  however,  that  unfavorable  weather 
conditions  have  nothing  to  do  with  the  prominence  of  this  dis- 
ease, which  they  suspect  to  be  a  recent  importation  into  this 
country  from  Japan.  If  this  theory  is  true,  then  we  are  just 
beginning  to  feel  the  ejffects  of  its  devastation  in  this  state. 
Personally,  we  have  not  yet  found  convincing  proofs  to  cause 
us  to  change  our  views  expressed  in  the  above-mentioned  Report. 
These  views,  briefly  given,  are  (i)  that  the  fungus  is  a  native, 
weak  parasite,  usually  very  inconspicuous  in  its  damage,  and 
therefore  rarely  noticed;  and  (2)  that  the  unusual  winter  of 
1904,  by  severely  injuring  chestnut  trees,  gave  it  a  chance  to 
spring  into  unusual  and  sudden  prominence,  which  it  has  since 
maintained  and  even  increased  by  reason  of  four  successive  years 
of  drought,  that  have  injured  not  only  chestnuts,  but  many  other 
trees. 

We  do  not,  and  never  have,  questioned  its  seriousness.  Trees 
that  have  been  marked  in  two  localities  by  the  botanical  and 
the  forestry  departments  have  uniformly  showed  injury  greatly 
in  excess  of  that  indicated  when  first  examined.  If  our  theory 
is  correct,  we  do  believe,  however,  with  the  return  of  several 
normally  wet  years  the  trouble  will  gradually  grow  less  rather 
than  more  conspicuous  as  it  should  if  weakened  vitality  of  the 
trees  has  nothing  to  do  with  its  development. 

ELM,  Ulmus  americana. 

Leaf  Spot_,  Gnomonia  Ulmea  (Schw.)  Thuem.  Plate  XXXIV. 
During  the  summer  of  1909  several  complaints  came  to  the 
station  of  elm  trees  shedding  their  leaves  where  the  elm  leaf 


7i8    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

beetle  had  not  been  at  work.  The  most  serious  injury  seemed 
to  occur  in  the  vicinity  of  Chapinville.  At  the  request  of  Mr. 
Walter  Angus,  manager  of  the  Scoville  estate  at  that  place,  Mr. 
Walden  first  visited  there  in  August,  and  as  he  found  no  insect 
responsible  for  the  trouble  the  writer  made  an  investigation 
early  in  September  to  determine  if  a  fungus  was  the  cause  of 
it.  By  July,  or  earlier,  some  of  the  trees  had  almost  entirely 
shed  their  leaves,  and  later  put  forth  a  new  crop,  and  these, 
when  examined  by  the  writer,  were  quite  free  from  fungous 
attack.  Other  trees,  however,  not  originally  so  severely  injured, 
showed  the  leaves  quite  badly  infected  with  the  above  fungus, 
and  these  had  been  shedding  their  leaves  more  or  less  during 
the  season.  Where  the  defoliation  had  been  rather  severe,  the 
young  branchlets  of  the  season  had  also  frequently  fallen  off. 
While  the  fungus  was  present  on  some  trees  more  than  on 
others,  and  while  some  of  the  fallen  leaves  showed  no  sign  of 
the  fungus,  it  seemed  quite  evident,  after  a  careful  examination, 
that  this  fungus  was  primarily  responsible  for  the  trouble,  but 
that  drought  had  helped  to  exaggerate  it.  The  illustration  shows 
the  condition  as  regards  foliage  of  one  of  the  trees  photo- 
graphed by  Mr.  Walden  in  August. 

The  fungus  produces  very  numerous,  small,  black  eruptions 
on  the  upper  surface  of  the  leaves,  and  these  often  merge  more 
or  less  in  small  groups.  In  time  the  specimens  show  a  whitish 
or  grayish  margin  around  these  black  cushions,  due  to  the 
wearing  away  of  the  epidermis.  We  have  been  unable  to  find 
any  fruiting  stage  in  any  of  the  specimens  we  have  gathered 
in  different  years,  as  the  only  known  stage  produces  its  asco- 
spores  on  the  fallen  leaves  the  subsequent  spring.  Infection 
seems  to  take  place  only  early  in  the  season,  since  the  trees 
early  denuded  did  not  have  their  second  crop  of  leaves  attacked 
to  any  extent.  Apparently  the  weather  conditions  in  the  spring 
determine  the  character  and  amount  of  infection,  and  these 
conditions  seem  to  have  been  unusually  favorable  in  1909.  In 
1910,  on  the  same  estate  in  Chapinville,  the  fungus  did  practi- 
cally no  harm,  though  the  trees  bore  a  smaller  crop  of  leaves, 
due  to  the  shedding  of  the  small  twigs  the  previous  year  and 
to  the  death  of  others  that  were  severely  injured. 

Spraying  the  unfolding  leaves  with  Bordeaux  would  probably 
control  this  trouble,  though  the  uncertainty  of  its  appearance 
would  make  such  a  treatment  rarely  practical. 


NOTES    ON    PLANT   DISEASES   OF    CONNECTICUT.  719 

This  fungus  was  placed  by  Ellis  under  the  genus  Dothidella 
as  D.  Ulmea  (Schw.)  E.  &  E.  It  is,  however,  quite  distinct 
in  its  microscopic  appearance,  as  Ellis  states,  from  Dothidella 
Ulmi  (Duv.)  Wint.,  although  the  two  have  ascospores  very- 
similar.  The  latter  fungus  has  its  perithecia  embedded  in  a 
distinct  black  stroma,  and  the  necks  open  on  the  upper  surface 
of  the  leaves.  The  former,  by  the  crowding  of  the  perithecia 
together,  has  something  of  the  appearance  of  an  imperfect 
stroma,  while  the  perithecia  open  on  the  under  surface  of  the 
leaves  mature  their  asci  later,  and  apparently  have  no  other 
stage  connected  with  them. 

HEMLOCK,  Tsuga  canadensis. 

Hemlock-Heath  Rust,  Pucciniastrum  Myrtilli  (Schum.) 
Arth.  (I.  Peridermium  Peckii  Thuem.)  The  I  stage  of  this 
fungus  (see  Report  1907,  pp.  350,  383),  which  is  not  uncommon, 
though  rarely  abundant,  in  this  state  on  hemlock,  has  now  been 
connected  by  us,  through  artificial  infections,  with  the  H  and 
III  stage  of  the  above  Pucciniastrum,  which  we  found  in  19 10 
for  the  first  time  on  various  species  of  blueberry  and  huckleberry. 
Pucciniastrum  minimum  on  cultivated  azaleas,  also  found  here 
(see  Reports  1907,  p.  392  and  1908,  p.  854),  is  probably  not 
distinct  from  this  Pucciniastrum. 

PEACH,  Prunus  Persica. 

Spray  Injury.  Sturgis  (Report  1900,  p.  219)  has  recorded 
spray  injury  to  the  foliage  of  peach  by  Bordeaux  and  other 
fungicides  used  in  his  experiments  to  prevent  peach  rot  and 
scab.  He  found  potassium  sulphide  to  be  about  the  least 
injurious  fungicide  when  used  at  the  rate  of  i  lb.  to  50  gallons 
of  water.  In  our  experiments  with  spraying  peaches  in  1910, 
this  strength  was  used,  and  very  little  injury,  except  shot-holes 
in  a  few  of  the  leaves,  resulted.  However,  when  arsenate  of 
lead  (rate  of  3  lbs.  to  50  gallons  potassium  sulphide)  or  Paris 
green  (i  lb.  to  100)  was  added,  the  most  serious  injury  resulted. 
Not  only  were  the  leaves  badly  injured  by  shot-holes,  but  in 
time  they  all  fell  off.  Many  of  the  young  twigs  were  also  badly 
spotted  (purplish  spots  much  like  those  produced  by  the  scab 
fungus),  arid  some  were  killed.  A  few  young  trees  were  so 
severely  injured  that  they  finally  died. 


720    CONNECTICUT   EXPERIMENT   STATION    REPORT,    I9O9-I9IO. 

Very  similar  results  were  obtained  when  either  of  these  insecti- 
cides was  used  with  "Sulfocide."  This  spray,  even  when  used 
without  them,  at  a  rate  of  i  to  200  produced  more  or  less  injury, 
and  even  some  on  young  trees  at  i  to  400.  With  both  potassium 
sulphide  and  "Sulfocide"  the  injury  resulting  from  the  addition 
of  the  poisons  was  due  to  the  production  of  a  soluble  arsenate 
which  burned  the  tissues. 

PINE,  WHITE,  Pinus  Strobus. 

So-called  "Blight."  In  our  Report  for  1907,  page  353,  we 
described  the  white  pine  "blight,"  which  was  general  that  year 
not  only  in  Connecticut  but  all  over  New  England.  We  took 
the  view  that  it  was  a  physiological  trouble  due  to  adverse 
weather  conditions  (such  as  winter,  drought,  and  frost  injuries), 
though  there  were  those  who  believed  that  it  was  of  a  contagious 
nature,  due  to  fungous  attack.  We  now  have  data  at  hand 
to  prove  that  we  were  correct.  In  general  this  disease  becomes 
evident  by  the  leaves  being  killed  to  a  greater  or  less  extent 
from  their  tip  downward,  the  dead  portion  turning  reddish 
brown,  and  also  by  the  undersized  leaves,  which  remain  bunched, 
due  to  the  failure  of  the  branches  to  lengthen  out. 

That  the  disease  is  not  contagious  was  suggested  strongly  in 
our  previous  studies,  since  leaves  on  one  tree  may  all  be  badly 
affected  while  those  of  an  adjacent  tree  show  no  signs  of  the 
trouble.  This  noncontagious  nature  has  been  clearly  proved  by 
observations  made  in  the  station's  forest  plantation  on  a  lot  of 
white  pine  trees  eight  years  old,  in  1910,  from  planting.  At 
our  request  the  forester,  Mr.  Hawes,  early  in  the  spring  of 
1908  had  all  the  diseased  trees  of  this  plot  marked  by  permanent 
stakes.  There  were  one  hundred  and  twenty-four  of  these  so 
marked,  but  it  seems  quite  likely  that  some  few  that  showed 
the  disease  slightly  at  the  time  were  not  included.  We  examined 
them  that  fall,  and  found  that  their  condition  on  the  whole 
seemed  somewhat  improved,  and  that  there  was  no  general 
increase  of  the  trouble,  though  some  trees  that  had  not  been 
marked  showed  signs  of  the  disease.  In  July,  1909,  and  again 
in  November,  19 10,  careful  examinations  were  made  of  the 
plot,  and  the  condition  of  each  diseased  tree  noted.  The  com- 
parative condition  of  these  trees  as  regards  foliage  is  shown 
in  the  following  table : 


NOTES    ON    PLANT   DISEASES   OF    CONNECTICUT.  72  1 

Diseased,  but 
Date  of  not  marked  Not 

Examination  in  1908  Dead  Improved  Improved  Cured  Total 

July,  1909 24        5       54       38       21      142 

Nov.,  1910 18        6       9       65       44      142 

This  shows  that  there  has  bten  gradual  improvement  since 
the  trouble  first  showed  in  1907,  and  that  there  has  been  practi- 
cally no  subsequent  spreading  of  the  trouble.  That  is,  in  19 10 
there  were  only  eighteen  trees  showing  the  disease,  among  the 
3,000  to  3,200  in  the  plot,  that  did  not  show  it  in  the  spring  of 
1908.  Of  these  eighteen,  at  least  thirteen  were  included  as 
questionable;  that  is,  there  was  not  positive  evidence  that  it 
was  this  trouble,  as  the  leaves  were  only  slightly  affected.  No 
doubt,  too,  some  of  these  were  trees  that  were  not  marked 
originally  because  they  were  not  badly  injured.  It  is  also  quite 
probable  that  some  were  trees  whose  leaves  were  injured  by 
the  frosts  of  1910,  of  which  we  shall  speak  later,  as  the  injured 
leaves  were  often  largely  on  lower  branches.  Finally,  there 
was  no  relationship  in  position  between  these  trees  and  those 
badly  diseased. 

Concerning  the  effect  of  the  so-called  "blight"  on  the  sub- 
sequent growth  of  the  trees,  we  may  state  that  those  that  were 
very  badly  injured  have  either  died,  or  remained  so  stunted 
in  growth  that  their  subsequent  usefulness  is  quite  doubtful. 
Others  that  were  rather  severely  injured  have  made  some 
growth,  and  their  foliage  condition,  especially  as  to  color,  has 
improved  considerably,  though  the  leaves  often  remain  more  or 
less  stunted  and  bunched.  Those  least  injured  have  recovered 
their  normal  leaf  appearance,  but  are  still  somewhat  backward 
in  their  growth.  Some  few  seem  to  have  almost  entirely  recov- 
ered from  the  effects,  and  are  scarcely  to  be  distinguished  in 
size  and  appearance  from  the  surrounding  trees  that  were  not 
injured. 

Concerning  the  cause  of  the  sudden  appearance  of  this 
"blight"  in  1907,  we  are  now  quite  convinced  that  it  was  due 
to  the  severe  frosts  that  occurred  on  May  11  and  21  of  that 
year.  We  mentioned  these  as  a  possible  cause  in  our  previous 
Report,  but  at  that  time  we  had  no  proof  as  to  their  connection, 
as  the  "blight"  was  not  called  especially  to  our  attention  until 
August.  In  1910,  however,  we  saw  the  same  trouble  produced 
on  certain  pines  by  the  late  frosts  of  May  and  June  of  that 
year.     Soon  after  these   frosts  we   found  the   leaves   of   scrub 


722    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

oaks  in  certain  regions  entirely  killed  by  the  frosts,  just  as  had 
been  the  case  with  the  leaves  of  sycamore  trees  in  1907.  In 
1910,  however,  the  frosts  were  much  more  local  in  their  effects, 
and  in  a  given  region  often  killed  the  leaves  only  on  the  lower 
trees  and  the  shrubs,  especially  those  in  low  places.  Shortly 
after  the  last  of  these  frosts  we  visited  the  white  pine  planta- 
tions on  the  Whittemore  estate  at  Middlebury,  and  here  we 
found  not  only  small  oaks  and  other  trees  in  low  spots  with 
injured  foliage,  but  also  the  young  pines  in  these  low  places 
showed  "blight"  injury  on  the  tips  of  their  leaves.  Often  a 
difference  of  only  a  few  feet  in  the  level  of  the  ground  on 
which  these  stood  determined  whether  or  not  they  were  injured. 
We  have  also  noted  elsewhere  in  this  Report  injury  by  these 
frosts  to  pine  seedlings  in  the  seed  beds.  Whether  or  not  a 
pine  tree  is  injured  by  the  late  frosts  seems  to  be  determined 
by  the  state  of  development  of  the  foliage  at  the  time,  as  well 
as  by  the  lay  of  the  land  and  the  character  of  the  frost. 
Previous  to  1907  we  had  some  few  complaints  of  pine  "blight," 
which  we  may  attribute  to  winter  injury  of  the  roots,  and  no 
doubt  drought  or  other  injury  to  the  roots,  if  severe,  produces 
a  similar  effect.  Hartig,  in  his  Diseases  of  Trees,  English  ed., 
p.  Ill,  notes  a  similar  "blight"  trouble  in  Europe,  due  to  frost 
and  drought  injury. 

PLTJM,  Prunus  sp. 

Bacterial  Spot,  Pseudomonas  Pruni  Sm.  This  has  been 
reported  here  before  on  peach,  causing  spots  on  the  leaves,  and 
on  the  plum,  causing  large  black  spots  on  the  fruit.  In  July, 
1910,  it  was  seen  at  the  Ives  farm,  Meriden,  for  the  first  time 
causing  a  shot-hole  spotting  of  plum  leaves,  similar  to  that 
not  uncommon  on  the  peach. 

SPRUCE,  NOEWAY,  Picea  excelsa. 

Smoke  Injury.  During  the  summer  of  1910  the  writer  saw 
young  spruce  trees  at  East  Rock  Park,  New  Haven,  that  had 
been  injured  by  smoke  from  a  brick  kiln  about  half  a  mile 
distant.  The  injury  occurred  suddenly  on  a  day  when  the  atmos- 
pheric conditions  were  just  right  for  blowing  the  smoke  among 
the  trees.  The  young  leaves  of  this  year  were  killed  and  sub- 
sequently  dropped   off,   but   those   of   the   previous  •  year   were 


NOTES   ON    PLANT   DISEASES    OF    CONNECTICUT.  723 

not  injured.  Some  other  conifers  were  also  slightly  injured, 
but  the  deciduous  trees  escaped  injury,  though  in  the  vicinity 
of  the  kiln  the  maples  and  other  trees  are  sometimes  injured. 
Previous  smoke  injury,  complicated  with  drought  injury,  to 
asparagus  fields  in  the  vicinity  of  this  kiln,  was  mentioned  in 
our  Report  for  1908,  page  858,  and  similar  injury  is  claimed 
to  have  been  caused  again  this  year. 


C.     DISEASES  OR  HOSTS  NOT  PREVIOUSLY  REPORTED. 

APPLE,  Pyrus  Mains. 

Fruit  Spot,  Cylindrosporium  Pomi  Brooks.  Plate  XXXIII  a. 
In  our  Reports  for  1905,  page  264,  and  1907,  page  340,  we 
described  a  fruit  speck  of  apples  that  formed  small,  brownish, 
spots  in  the  skin  of  apples,  being  especially  prominent  after  stor- 
age. Cultures  proved  this  trouble  to  be  of  fungous  origin,  but  as 
these  cultures  did  not  produce  a  fruiting  stage  of  the  fungus,  we 
were  not  sure  of  its  identity. 

More  recent  study  has  shown  that  there  are  three  fungi  that 
occur  in  fruit  spots  or  specks  of  apples.  One  of  these  is  the 
black  rot  fungus,  Sphaeropsis  Malorum,  which  is  more  commonly 
known  not  as  a  spot  trouble,  but  as  a  general  rot  of  the  fruit, 
especially  on  summer  and  fall  varieties  following  insect  injury. 
This  fungus  is  the  one  that  we  have  most  commonly  isolated  from 
the  fruit  specks  of  market  apples.  Ordinarily  it  does  not  fruit 
in  the  culture  media  on  which  we  have  grown  it,  and  so  it  was 
probably  largely  responsible  for  the  fruit  speck  we  describe  in 
the  above  reports,  though  Cylindrosporium  Pomi  was  possibly 
present  in  some  cases.  Besides  the  black  rot,  we  have  also  occa- 
sionally isolated  a  species  of  Alternaria  which  seems  to  be  respon- 
sible for  speck  injury,  though  we  have  as  yet  made  no  inoculation 
tests  to  prove  this. 

.  The  third  fruit  spot,  which  we  have  seen  frequently  on  the 
fruit  before  it  was  gathered  from  the  trees,  as  well  as  afterwards, 
is  that  caused  by  Cylindrosporium  Pomi,  which  was  described  a 
few  years  ago  as  a  new  species  by  Brooks,  who  found  it  respon- 
sible for  a  serious  spotting  of  apples  in  New  Hampshire.  This 
fruit  spot  on  the  market  apples  is  usually  very  difficult  to  distin- 
guish from  that  of  the  black  rot.     Perhaps  the  black  rot  fungus 


724    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

may  finally  crowd  it  out  in  many  cases.  However,  on  certain  light 
skinned  varieties,  especially  seedlings,  it  shows  in  the  summer  as 
small  spots  in  the  skin  having  a  decidedly  pinkish  or  reddish 
purple  color.  We  have  seen  roadside  seedlings  made  very  con- 
spicuous by  it  in  late  fall.  In  storage  the  color  of  the  spots  is 
darker.  So  far  we  have  not  seen  the  fungus  in  fruit  on  these 
superficial  spots,  and  ordinarily  they  do  not  seem  to  reach  any 
considerable  size,  except  perhaps  when  developed  further  by  the 
presence  of  the  black  rot  fungus.  In  one  instance  we  isolated 
this  Cylindrosporium  from  market  quinces,  a  new  host,  and  we 
have  frequently  seen  similar  spots,  showing  no  fruiting  fungus, 
on  quinces  before  and  after  picking. 

On  our  oat  juice  agar  medium  the  fungus  forms  a  large,  yeast- 
like, pinkish  colony  with  no  aerial  growth,  but  producing  an 
abundance  of  spores.  With  age  it  turns  a  darker  color,  sometimes 
black,  though  in  such  cases  it  may  be  due  to  the  presence  of 
another  fungus  frequently  associated  with  it,  which  we  have 
isolated,  but  whose  identity  has  not  yet  been  determined. 

AZALEA,  Rhododendron  indicum. 

Pocket  Curl,  E.vobasidium  Vaccinii  (Fckl.)  Wor,  Plate 
XXXIII  b.  Galls  and  hypertrophy  caused  by  this  or  closely 
related  species  are  not  uncommon  in  this  state  on  various  wild 
species  of  the  heath  family,  but  this  fungus  on  a  cultivated 
species  was  called  to  our  attention  for  the  first  time  in  the  fall 
of  1909.  Specimens  of  the  above  azalea,  purchased  a  few  months 
previously  for  a  private  greenhouse,  were  very  badly  injured. 
These  plants  were  apparently  infected  when  purchased,  having 
been  grown  out  of  doors  in  a  neighboring  state,  but  did  not 
show  the  trouble  at  that  time.  The  disease  appeared  on  th'b 
leaves,  usuahy  involving  the  apical  part  and  causing  a  decided 
thickening  of  the  tissues.  This  infected  part  covered  more  or 
less  of  the  leaf,  which  often  became  decidedly  concavo-convex, 
as  shown  in  the  illustration.  The  infected  tissues  were  quite 
sharply  marked  off  from  the  healthy  part,  both  by  their  dis- 
tortion and  by  their  whitish  color,  being  eventually  covered  by 
a  mealy  coating  of  spores,  etc. 

Cultures  were  made,  and  a  fungus  obtained  that  seems  to 
be  a  conidial  stage  of  this  fungus,  though  its  identity  has  not 
been  thoroughly  established. 


NOTES   ON    PLANT  DISEASES   OF   CONNECTICUT.  725 

The  question  whether  or  not  the  various  forms  of  Exohasidium 
found  on  the  different  genera  of  the  heaths  are  distinct  or  not 
has  not  been  definitely  decided.  Often  their  macroscopic 
appearance  on  different  hosts  is  quite  distinct,  but  as  Richards 
(Bot.  Gaz.  21:  loi.  1896)  succeeded  in  producing  the  ordinary- 
leaf  form  from  spores  of  the  unusual  large  bladder  form  on  a 
different  host,  it  looks  to  the  writer  as  if  these  differences  were 
largely  due  to  the  age  or  parts  of  the  host  infected.  Shirai 
has  described  two  species  of  Exohasidium  on  Rhododendron 
indicum,  to  one  of  which  our  fungus  possibly  may  belong  if 
they  are  really  distinct,  though  the  spore  measurements  do  not 
seem  to  agree  entirely. 

CELERIAC,  Apium  graveolens  var.  rapaceum. 

Leaf  Blight,  Cercospora  Apii  Fr.  We  have  reported  before, 
on  celeriac,  the  leaf  spot  due  to  Septoria,  but  not  this  fungus. 
Both  produce  brownish  or  grayish  spots  of  considerable  size 
on  the  leaves,  often  causing  them  to  turn  yellow  and  die  pre- 
maturely. They  are  often  found  associated,  the  Cercospora 
being  distinguished  by  its  minute  threads  arising  from  the 
surface  of  the  leaves,  while  the  Septoria  forms  small,  embedded, 
black  specks. 

CHESTNUT,  Castanea  sps. 

Chestnut  Bark  Disease,  Diaporthe  parasitica  Murr.  Speci- 
mens of  this  serious  disease  of  our  native  chestnuts  have  been 
collected  on  the  Japanese  chestnut,  Castanea  japonica,  in  a  local 
■  nursery.  Dr.  R.  T.  Morris,  who  grows  a  large  number  of 
varieties  of  chestnuts  on  his  Stamford  farm,  also  reports  (Conn. 
Farmer,  March  ii,  1911,  p.  2)  that,  besides  the  Japanese  species, 
the  European  species,  Castanea  sativa,  and  the  American  Chin- 
quapin, Castanea  pumila,  have  been  more  or  less  subject  to  this 
blight  at  this  place.     See  page  716  of  this  Report. 

CHESTNUT,  Castanea  dentata. 

Powdery  Mildew,  Microsphcora  Alni  (Wallr.)  Wint.  We 
have  not  reported  this  host  because  we  have  found  the  mildew 
on  it  previously  only  in  the  woods,  but  in  September,  1907, 
it  Avas  observed  on  cultivated  trees  in  a  small  nursery  at  Storrs. 
It  forms  evident,  mealy,  whitish  growths,  in  which  the  perithecia 


726    CONNECTICUT    EXPERIMENT    STATION    REPORT,    I909-I9IO. 

are  embedded  as  small  black  specks,  chiefly  on  the  upper  surface 
of  the  leaves.     It  is  not  an  important  disease  of  this  host. 

CHIVES,  Allium  Schccnoprasum. 

Rust,  Puccinia  Porri  (Sow.)  Wint.  This  rust  was  collected 
by  Dr.  Britton  during  June,  1910,  on  chives  in  his  garden  in 
Westville,  where  it  was  doing  considerable  injury  to  the  plants. 
Both  the  II  and  III  stages  were  present,  the  former  showing 
as  minute,  reddish,  dusty  pustules,  and  the  latter  as  black,  granu- 
lar ones,  more  permanently  covered  by  the  epidermis.  The 
leaves,  when  fairly  abundantly  infected,  turned  yellow  and  died 
prematurely.  I  have  not  seen  any  account  of  injury  by  this 
rust  to  cultivated  species  of  Allium  in  this  country,  though  in 
Europe  it  is  not  uncommon.  Worthington  Smith,  in  his  Dis- 
eases of  Field  and  Garden,  page  39,  mentions  it,  under  the  name 
Puccinia  mixta  Fckl.,  as  causing  serious  injury  to  a  crop  of  chives 
in  England.  There  is  more  or  less  difficulty  in  deciding  the 
proper  genus  of  this  fungus,  since  the  telial  spores  in  some 
specimens  on  certain  hosts  are  almost  or  entirely  single-celled, 
and  so  properly  come  under  the  genus  Uromyces;  other  speci- 
mens show  these  spores  largely  two-celled,  and  so  place  it  more 
properly  under  the  genus  Puccinia.  Our  specimens  run  more 
nearly  to  the  former  type,  as  not  over  one  or  two  per  cent, 
of  the  spores  are  two-celled.  Winter  considered  the  two  as 
a  single  species,  and  we  have  followed  him.  Other  writers 
place  the  single-celled  form  under  Uromyces  ambiguus  (DC.) 
Fckl.,  and  the  form  with  most  of  its  spores  two-celled  under 
Puccinia  Porri,  as  given  here.  The  rust  on  chives  in  Europe 
is  generally  reported  under  this  latter  name.  Our  specimens, 
however,  have  fewer  two-celled  spores  than  those  we  have  seen 
from  Europe  on  the  same  host.  Puccinia  Allii  (DC.)  Rud., 
also  on  species  of  Allium,  is  quite  a  different  fungus. 

CORNFLOWER,  Centaurea  Cyanus. 

Rust,  Puccinia  Cyani  (Schl.)  Pass.  Both  the  II  and  III 
stages  of  this  rust  were  found,  causing  severe  injury  to  the 
cornflowers  in  the  writer's  garden  during  the  summer  of  1909. 
The  sori,  while  numerous,  form  rather  inconspicuous,  dusty 
outbreaks   on   both   surfaces   of   the   leaves  and   on   the   stems 


NOTES   ON    PLANT   DISEASES   OF    CONNECTICUT.  727 

Apparently  this  fungus  has  rarely  been  reported  in  this  country. 
Another  rust,  P.  Centaurece  DC,  also  occurs  on  other  species 
of  Centaurea  both  here  and  in  Europe.  Both  of  these  species 
have  frequently  been  grouped  with  other  Puccinias,  the  species 
here  reported  being  usually  placed  under  P.  suaveolens,  along 
with  the  rust  on  Cnicus  now  commonly  known  by  that  name. 

ELM,  Ulmus  sp. 

Anthracnose^  Septoglceum  Ulmi  (Fr.)  Br.  and  Cav.  This 
fungus  was  found  on  an  escaped  seedling  of  Ulmus  campestris 
(apparently)  along  the  roadside  in  Centerville.  It  produces 
numerous,  minute,  at  first  yellowish  but  finally  reddish-brown 
spots  on  the  upper  surface  of  the  leaves,  while  below  the 
fruiting  stage  shows  as  minute,  glistening,  yellowish  globules. 

The  fungus  has  usually  been  reported  as  Phleospora  Ulmi 
(Fr.)  Wallr.,  but  the  writer  agrees  with  Briosi  and  Cavara 
that  it  belongs  more  properly  under  the  above  genus.  Cylindro- 
sporium  ulmicolum  Ell.  and  Ev.  possibly  is  not  distinct  from 
this  species,  as  its  description  is  very  similar.  This  Septoglceum 
is  thought  by  some  writers  to  be  the  spermagonial  and  Piggotia 
astroidea  B.  and  Br.,  the  pycnidial  stage  of  Dothidella  Ulmi 
(Duv.)  Wint.  [Phyllachora  Ulmi  (Duv.)  Fckl.],  though  neither 
of  these  two  stages  were  found  associated  with  our  specimens. 
The  asco  stage  of  Dothidella  Ulmi,  while  not  uncommon  in 
Europe,  does  not  seem  to  have  been  reported  in  this  country 
except  the  doubtful  specimen  sent  by  Torrey  to  Schweinitz. 

GOOSEBERRY,  Ribes  sp. 

Rust,  ^cidium  Grossularice  (Pers.)  Schum.  This  rust  was 
found  on  the  leaves  of  a  species  of  gooseberry,  apparently 
escaped  from  cultivation,  in  the  woods  of  an  abandoned  farm 
belonging  to  the  water  company  at  Ansonia.  The  fungus  forms 
rather  small  clusters  of  cup-shaped  fruiting  bodies  on  the  under 
surface  of  the  leaves,  producing  discolored  spots  above.  It  is 
probably  connected  with  some  species  of  Puccinia  on  Carex 
as  its  mature  stage,  as  has  been  found  to  be  the  case  with  several 
European  forms  on  Ribes  sp.  We  have  never  seen  this  ^cidium 
causing  much  harm  to  its  hosts,  and  it  seems  to  occur  chiefly 
on  the  wild  species. 

51 


728    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I9O9-I9IO. 

HOESECHESTNTJT,  ^sculus  sps. 

Powdery  Mildew,  Uncinula  flexuosa  Pk.  This  mildew  was 
found  on  a  species  of  Msculus  with  colored  blossoms,  on  an 
estate  at  Chapinville  in  the  fall  of  1909.  The  conidial  stage 
formed  a  conspicuous  whitish  coating  on  the  upper  surface  of 
the  leaves,  while  the  perithecia  were  less  prominent,  though 
abundant,  on  the  lower  surface.  The  fungus  has  not  been 
reported  by  us  before,  though  Thaxter  collected  it  in  New 
Haven  in  1888  on  another  cultivated  species,  ^sculus  Hippo- 
castanum. 

MONKSHOOD,  Aconitum  Fischeri. 

Stem  Rot,  ?  Hypochnus  sp.  In  our  Report  for  1907,  page  351, 
we  described  this  stem  rot,  which  was  found  on  a  variety  of 
herbaceous  plants  in  a  local  nursery.  This  year  it  was  sent 
to  us  from  Westbrook,  where  it  was  injuring  specimens  of 
larkspur,  one  of  the  hosts  reported  before.  Since  our  first 
report  we  have  also  found  it  on  monkshood,  in  the  same  nursery 
where  it  was  found  originally.  So  far  we  have  been  unable 
to  identify  the  fungus,  as  our  cultures  form  only  the  sclerotial 
stage — small,  reddish,  usually  subspherical  bodies  about  2  to 
5  mm.  in  diameter.  We  have  a  similar  fungus  from  potato 
stems,  forming  considerable  small  sclerotia,  that  was  given  to 
us  by  Morse  of  the  Maine  Station.  While  in  Japan,  we  saw 
in  Professor  Hori's  laboratory  artificial  cultures  of  a  number 
of  these  sclerotial  fungi,  which  he  had  described  as  species 
of  Hypochnus,  though  we  are  not  sure  of  this  identification 
from  what  we  have  learned  concerning  them. 

PINE,  Pinus  sps. 

Pine-Oak  Rust,  Cronartium  Quercus  (Brond.)  SchrcKt. 
(L  Peridermium  cerebrum  Pk.)  On  specimens  of  jack  pine, 
Pinus  Banksiana,  in  the  nursery  of  the  station  forest  plantation 
at  Rainbow  in  the  spring  of  1910,  Mr.  Filley,  and  later  the 
writer,  collected  the  I  stage  of  this  fungus.  These  seedlings 
were  about  four  years  old,  and  had  been  brought  in  1908  from 
Michigan,  where  no  doubt  they  were  originally  infected,  as 
this  fungus  in  none  of  its  stages  has  ever  before  been  found 
in    this    state.      The    fungus    on    the    pine    forms    conspicuous 


NOTES   ON    PLANT   DISEASES   OF    CONNECTICUT.  729 

swellings,  usually  globular  in  shape,  and  in  early  spring  the 
fruiting  stage  shows  under  the  denuding  bark  as  orange-colored, 
dusty  spore  masses,  with  the  peridia  rarely  forming  distinct  cups, 
as  in  the  next  species.  The  II  and  III  stages  occur  on  species 
of  oak.  So  far  as  could  be  seen,  these  did  not  appear  on 
the  oaks  in  the  vicinity,  and  as  all  the  infected  pines  were 
destroyed,  it  is  not  likely  to  become  established  there.  Infec- 
tion experiments  made  in  the  laboratory  from  the  I  stage, 
however,  produced  the  III  stage  only  very  readily  on  seedlings 
of  both  red  and  white  oaks.  So  far  this  fungus  has  not  done 
much  damage  elsewhere  on  either  host.     See  Plate  XXXVI  b. 

PiNE-SwEETFERN  RusT,  Cronavtium  Comptonice  Arth.  (I. 
Peridermium  pyriforme  Pk.)  In  the  Report  of  1907,  page  380, 
the  writer  reported  the  I  stage  of  this  rust  on  both  Pinus  rigida 
and  P.  sylvestris  from  this  state.  It  had  become  established 
on  the  latter  host  in  the  station  forest  plantation  at  Rainbow. 
In.ipio  it  was  found  there  also  on  Pinus  rigida,  P.  austriaca, 
and  P.  maritima.  It  was  also  found  in  its  II  and  III  stages 
on  the  sweetfern,  to  which  it  had  spread  since  its  introduction. 
Apparently  most  of  these  pines  had  become  infected  in  their 
nursery  beds  at  Poquonock  before  transplanting  here  some 
years  ago,  as  thousands  of  seedlings  of  Pinus  rigida  grown  from 
the  first  in  their  vicinity  showed  practically  no  infection.  The 
specimens  of  P.  maritima,  however,  had  become  infected  there 
in  their  seed  bed,  yet  we  could  find  no  infected  sweetfern  in 
their  immediate  vicinity  this  year.  In  order  to  prevent  further 
spread  of  the  rust,  all  infected  pines  were  destroyed  or  the 
infected  branches  cut  off,  and  the  forester  had  all  the  sweetfern 
in  the  vicinity  mowed  off.  Most  of  the  pines,  having  the  fungus 
on  their  main  trunk,  were  of  little  value.  Where  infection 
takes  place  after  the  pines  are  a  few  years  old,  the  damage  is 
not  likely  to  be  nearly  so  severe  as  when  it  takes  place  in  the 
seed  bed.    See  Plate  XXXVI  c. 

PIITE,  WHITE,  Pinus  Strobus. 

Drought  Injury.  In  the  fall  of  1909,  Mr.  Spring  noticed  a 
few  spots  in  one  of  the  seed  beds  at  the  station  forest  plantation 
where  the  white  pine  had  been  entirely  killed  out  for  the  space 
of  a  few  inches.  Specimens  of  these  and  some  of  the  adjacent 
living  pines  were  brought  to  the  writer  at  the  time  for  examina- 


73°     CONNECTICUT   EXPERIMENT   STATION    REPORT,    I909-I91O.      . 

tion.  On  the  stems  of  the  dead  pines,  and  also  somewhat  on 
the  Hving  ones,  was  a  conspicuous  felt  of  mycelium  of  a 
hymenomycetous  fungus  which  Professor  E.  A.  Burt  determined 
as  Coniophora  byssoidea  (Pers.)  Fr.  At  first  we  thought  that 
this  fungus  was  responsible  for  the  death  of  the  seedlings,  but 
we  were  unable  to  find  any  account  of  injury  caused  by  it 
elsewhere.  A  bunch  of  these  young  pines  was  kept  in  a  crock 
in  the  greenhouse  for  several  months,  and  there  was  no  indi- 
cation that  the  fungus  injured  the  healthy  young  pines  on  which 
it  originally  occurred,  or  that  it  spread  further.  The  fungus 
evidently  ran  up  on  the  stems  merely  as  a  saprophyte,  from 
various  leaves  on  the  ground  on  which  it  also  occurred.  The 
pines  in  the  seed  beds  were  probably  killed  by  the  drought, 
which  was  so  severe  in  1909,  and  the  dead  and  injured  seedlings 
offered  a  better  condition  for  the  development  of  the  fungus 
than  the  surrounding  mulch  of  leaves,  as  Professor  Burt  states 
that  out  of  nine  specimens  in  his  herbarium  seven  are  on  pine 
and  two  on  spruce.    See  Plate  XXXV  a. 

Frost  Injury.  Plate  XXXV  b.  In  examining  the  seed  beds  of 
white  pines  at  the  station  plantation  at  Rainbow  in  the  fall  of 
1910,  the  writer  found  sn^all  spots  scattered  in  the  beds  where 
the  leaves  of  this  year's  growth  had  been  killed.  The  injury 
was  evidently  caused  by  the  late  frosts  of  May  and  June  of 
that  year,  as  these  had  killed  the  leaves  of  the  scrub  oaks  in 
this  vicinity,  as  observed  at  the  time.  The  young  pines  had 
developed  their  terminal  branches  an  inch  or  two  in  length, 
and  these  had  been  severely  injured  or  killed  by  the  frost  on 
both  the  one-  and  two-year-old  seedlings.  The  leaves  of  the 
previous  year  remained  uninjured.  Afterwards  these  injured 
pines  put  out  several  lateral  buds  from  or  below  the  injured 
tip,  but  even  as  late  as  November  i,  when  seen  by  the  writer, 
these  had  not  usually  attained  a  length  of  half  an  inch.  This 
injury  had  severely  stunted  the  growth  of  the  plants  during 
the  season,  as  is  indicated  by  the  photograph,  which  shows 
one  of  the  uninjured  plants,  besides  several  of  the  injured  ones 
of  the  same  age.  A  few  seedlings  of  Pinus  montana  were  also 
injured,  but  not  so  extensively  as  were  those  of  the  white  pine. 

PiNE-CuRRANT  RusT,  Cronartium  ribicola  Waldh.  (I.  Peri- 
dermium  Strohi  Kleb.)  Plate  XXXVI  a.  In  our  article  on  Heter- 
cecious  Rusts  of  Connecticut,  published  in  the  Report  for  1907, 


NOTES   ON    PLANT   DISEASES   OF    CONNECTICUT.  731 

page  374,  we  mentioned  this  rust  as  one  likely  to  be  brought 
into  this  state  on  imported  white  pine  seedlings  from  Europe. 
Its  introduction  really  occurred  sooner  than  was  anticipated. 
Mr.  F.  A.  Metzger  first  found  specimens  on  a  lot  of  three-year- 
old  seedlings  from  Germany  that  had  been  imported  by  our 
State  Forester  for  Mr.  C.  F.  Street,  and  planted  at  Wilton. 
Mr.  Metzger,  who  was  employed  to  set  them  out,  found  in  the 
10,000  seedlings  from  fifty  to  one  hundred  that  were  infected 
with  the  rust.  He  brought  specimens  to  the  station  the  last  of 
April,  1909,  but  as  the  writer  was  in  Japan  at  that  time,  nothing 
further  was  done. 

In  the  meantime  Messrs.  Metcalf  and  Spaulding,  of  the  U.  S. 
Department  of  Agriculture,  who  had  been  looking  up  infected 
seedlings  in  other  states,  came  to  this  state  about  the  middle 
of  June,  and  with  the  forester  examined  the  plantations  of  the 
New  Haven  Water  Company  at  West  Haven  and  the  Ansonia 
Water  Company  near  Ansonia,  and  found  a  few  very  suspicious 
specimens  at  these  places.  Arrangements  were  made  soon  after- 
ward by  which  Mr.  Spaulding  and  Mr.  Graves  for  the  Govern- 
ment and  the  botanical  department  for  the  station  undertook 
during  July  to  go  over  the  plantations  in  the  state  where  white 
pine  seedlings  had  been  imported  from  Europe,  and  inspect  them 
for  this  rust,  and  to  destroy  any  infected  seedlings,  if  found, 
and  any  wild  gooseberries  or  currants  in  their  vicinity,  as  the 
II  and  III  stages  occur  on  the  latter  as  alternate  hosts.  It 
was  really  then  too  late  in  the  season  to  find  the  fungus  on 
the  pines,  except  far  past  its  prime.  However,  twenty-four 
plantations,  including  about  580,000  seedlings,  were  inspected, 
and  very  suspicious  or  positively  identified  infected  specimens 
were  found  at  two  additional  places;  viz.,  at  the  Plant  estate 
plantation  at  East  Lyme  and  at  the  Groton  Water  Company 
plantation  at  Poquonock.  In  none  of  the  five  places  where 
signs  of  the  pine  rust  were  found  were  more  than  a  dozen 
specimens  seen,  except  at  the  Street  plantation,  where  the  dis- 
eased plants  were  noticed  as  they  were  being  set  out.  A 
descriptive  letter  concerning  the  rust  and  its  reputation  was 
sent  to  all  those  who  had  used  imported  seedlings. 

In  1910  the  botanical  and  forestry  departments  of  the  station 
undertook  to  again  go  over  these  and  other  plantations,  beginning 
early  in  the  season,  as  soon  as  the  rust  ordinarily  makes  its 


732    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

appearance.  During  May  and  June  four  inspectors  visited 
twenty-six  plantations,  inspecting  about  425,000  seedlings,  and 
made  very  careful  examinations  for  the  rust,  in  many  cases 
examining  every  individual  seedling.  In  spite  of  this  thorough 
examination,  not  a  single  rusted  plant  was  found!  No  doubt 
the  severe  drought  of  the  preceding  year  had  killed  off  those 
seedlings  weakened  by  the  rust,  if  such  existed.  Of  course 
it  is  possible  that  examination  another  year  might  reveal  a  few 
rusted  plants,  as  it  is  usual  for  the  seedlings  to  go  one  or 
possibly  more  years  after  infection,  before  the  secial  stage  of 
the  rust  appears  on  them. 

During  the  years  1907,  1908  and  1909,  there  were  imported 
into  the  state,  chiefly  from  Germany,  under  the  supervision  of 
the  station's  forestry  department,  about  640,000  white  pine 
seedlings,  which  were  set  out  in  fifty-five  different  localities, 
and  private  individuals  have  imported  at  least  100,000  more. 
All  of  these  seedlings,  except  about  95,000  set  out  mostly  in 
small  lots  in  twenty  different  localities,  have  now  been  inspected 
once  or  twice  for  the  rust.  No  doubt,  too,  at  the  time  they 
were  set  out  the  men  would  have  discarded  any  specimens 
showing  evidence  of  the  rust.  In  all  of  the  plantations  exam- 
ined, watch  was  kept  for  any  signs  of  currants  or  gooseberries 
in  the  vicinity  of  the  pines,  and  these  were  destroyed  when 
found.  Fortunately,  species  of  Ribes  in  a  wild  or  escaped  state 
are  comparatively  rare  here,  so  that  even  if  this  rust  occurred 
on  the  pines,  it  would  be  much  more  difficult  for  it  to  pass 
to  these  hosts  than  in  some  of  the  more  northern  states 
where  they  are  more  frequent.  In  1910  the  station  did  not 
import  any  white  pines  because  of  the  danger  of  bringing  in 
this  rust,  and  only  one  lot,  to  our  knowledge,  was  imported  by 
others.  Examination  of  these  showed  no  signs  of  the  rust. 
From  now  on  it  is  probable  that  most  of  the  seedlings  set  out 
will  be  native  grown  stock,  as  plenty  of  this  seems  to  be  in 
evidence  at  fair  prices.  There  does  not  seem  to  be  much  likeli- 
hood, therefore,  that  the  rust  will  obtain  a  foothold  in  the 
state,  though  watch  will  still  be  kept  for  it.  Anyone  finding 
suspicious  specimens  should  send  them  to  the  station  for  exami- 
nation. 

Infected  white  pine  seedlings,  out  of  the  season  vv^hen  the 
fruiting  stage  appears,  may  be   recognized   in  a  general   way 


NOTES   ON   PLANT   DISEASES   OF    CONNECTICUT.  733 

by  the  somewhat  fusiform  swollen  stems  and  by  the  bunching 
of  the  leaves,  shown  by  the  halftones  in  Plate  XXXVI  a.  Not 
all  swellings  of  the  stem,  however,  are  due  to  rust,  as  insect 
and  other  injuries  may  produce  such  distortions  in  young  seed- 
lings. During  the  months  of  May  and  June  the  fruiting  stage 
shows  on  the  swollen  stems  as  small,  white,  oblong  blisters 
that  upon  rupture  reveal  an  orange  mass  of  spores.  These 
gradually  wear  away,  and  then  positive  evidence  of  infection 
is  more  or  less  difficult.  The  mycelium  remains  in  the  infected 
tissues,  gradually  spreading  to  the  new  growth,  and  renews  its 
fruiting  stage  each  spring,  unless  the  death  of  the  host  intervenes. 
The  spores  produced  on  the  pine  do  not  spread  the  disease  to 
other  pines,  but  develop  two  other  spore  stages  on  both  goose- 
berries and  currants,  the  last  stage  carrying  the  fungus  back 
to  the  pines. 

Many  writers  consider  this  rust  as  a  very  serious  menace 
to  white  pines.  The  writer  is  not  so  much  afraid  of  it  in  this 
state  because  of  the  scarcity  of  the  alternative  hosts,  and  also 
because  it  looks  to  him  as  if  most  of  the  damage  comes  from 
the  use  of  infected  seedlings,  which  we  should  be  able  to  largely 
eliminate  here.  Such  infection  as  might  occur  after  the  pines 
once  got  a  good  start  in  the  forests  we  are  inclined  to  believe 
would  be  rare,  and  not  nearly  so  injurious  to  the  host.  We 
have  heard  of  one  large  importer  of  white  pines  who  intends 
also  to  import  a  large  number  of  currant  bushes  for  commercial 
purposes.  Such  a  condition  offers  a  chance  for  the  rust  to  do 
considerable  harm  if  it  once  gets  started  in  either  of  his  plan- 
tations. 

The  native  pine-sweetfern  rust,  which  we  describe  elsewhere, 
seems  to  us  to  be  just  as  virulent  as  this  rust,  and  one  much 
more  likely  to  spread  generally  here,  on  account  of  the  frequency 
of  its  alternate  host,  the  sweetfern.  Yet,  with  the  exception  of 
the  plantation  at  Rainbow,  where  pines  were  infected  in  the  seed 
beds,  we  have  seen  and  heard  of  no  damage  by  this  rust.  This 
rust  does  not  occur  on  the  white  pine,  though  it  has  several 
other  species  for  its  hosts. 

PRIVET,  Ligustrum  vulgare. 

Anthracnose,  Glceosporium  cingulatum  Atk.*  Mr.  Coe,  of  the 
Elm  City  Nursery  Company,  first  called  the  writer's  attention 


734    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

to  this  disease  on  a  variety  of  privet  called  italicum,  which  was 
imported  from  France  in  the  spring  previous  to  our  examination 
in  the  fall  of  1910.'  The  fungus  causes  diseased  areas  on  the 
stem  and  branches,  which  are  not  very  conspicuous,  being  slightly 
sunken  and  a  different  color,  but  when  these  cankers  entirely 
girdle  the  branches,  the  leaves  and  finally  the  whole  branch  above 
die,  and  the  trouble  becomes  very  evident.  The  injury  at  this 
place  was  quite  noticeable,  through  the  dead  branches  and  one 
or  two  dead  bushes,  but  probably  the  shock  of  transplanting 
may  have  weakened  the  plants  so  that  the  trouble  was  more 
conspicuous  than  it  would  be  under  more  favorable  conditions 
for  the  host. 

When  Atkinson  originally  described  this  fungus  (Bull.  49, 
Cornell  Exp.  Sta.)  in  1892,  he  said  nothing  about  the  injury 
to  the  host,  and  we  have  seen  no  reference  where  it  is  said 
to  have  caused  conspicuous  injury,  though  it  seems  to  be  capable 
of  it.  Atkinson  obtained  cultures  of  the  fungus,  described  the 
conidial  stage,  and  suggested  that  it  had  a  mature  stage,  which 
his  student,  Miss  Stoneman,  later  described  (Bot.  Gaz.  26: 
loi.  1898)  as  belonging  to  the  genus  Gnomoniopsis,  now  known 
as  Glomerella. 

Cultures  of  the  fungus  were  easily  obtained  by  the  writer 
from  the  cankers,  and  these  produced  both  the  conidial  and  the 
asco  stages.  Miss  Stoneman  notes  the  presence  in  the  cultures 
of  setae  connected  with  the  conidial  stage,  but  did  not  find  these 
on  the  host.  The  writer,  however,  found  some  of  these  setae 
with  the  conidial  stage  on  the  host. 

RASPBERRY,  Ruhus  strigosus. 

Rust,  Puccinastrum  arcticum  var.  americanum  Farl.  This 
rust,  which  was  described  a  few  years  ago  by  Professor  Farlow 
(Rhodora  10:  13.  1908),  has  ordinarily  been  confused  with 
the  uredo  stage  of  Kueneola  alhida,  as,  like  that  species,  it  forms 
very  small  orange  outbreaks  on  the  under  side  of  the  leaves. 
Microscopically,  however,  the  two  are  quite  distinct.  The  uredo 
stage  was  sent  to  the  writer  from  Stamford  in  September,  1909, 
on  cultivated  raspberry,  this  being  the  first  time  it  has  been 
found  in  the  state.  It  apparently  did  little  harm  to  its  host. 
The  ^cial  stage 'is  unknown,  though  it  may  be  Peridermium 
balsameum  on  the  balsam  fir. 


NOTES   ON    PLANT   DISEASES    OF    CONNECTICUT.  735 

RYE,  Secale  cereale. 

Powdery  Mildew,  Erysiphe  graminis  DC.  In  our  Report 
for  1903  we  listed  the  conidial  stage  of  this  mildew  on  cultivated 
barley.  In  1910  specimens  on  rye  were  received  from  J.  F. 
Shepard,  of  New  Haven,  and  others  were  collected  by  the  writer 
at  the  station  farm  at  Centerville,  these  being  the  first  collections 
on  this  host  in  the  state.  In  the  latter  locality  the  perithecial 
stage  was  very  conspicuous  and  abundant  on  rye,  but  on  barley 
was  practically  absent.  Considerable  injury  was  caused  to  both 
these  hosts  through  severe  infection  of  the  leaves,  which  died 
prematurely.  Apparently  the  season  was  favorable  for  an 
unusual  development  of  the  fungus.  It  forms  an  evident 
grayish  felt  in  small  clusters,  thickly  covering  the  leaves,  and 
the  perithecia,  when  produced,  show  as  small  but  evident  black 
specks  embedded  in  this.  As  usual  with  this  species,  none  of 
the  asci  matured  their  spores  on  the  living  plants. 

SaUASH,  Cucurbita  Pepo. 

Chlorosis.  In  previous  Reports  we  have  mentioned  chlorosis 
troubles  of  Lima  and  string  beans,  muskmelon,  tobacco  and 
tomato.  Of  these  so  far  we  have  been  able  to  prove  only  those 
of  tobacco  and  tomato  to  be  infectious,  that  is,  capable  of 
producing  the  trouble  in  healthy  plants  when  juice  from  the 
chlorosis  plants  is  placed  on  the  young  leaves.  In  June,  1910, 
we  saw  plants  of  summer  squash  in  cold  frames  at  the  Farnham 
farm  in  Westville  that  were  subject  to  a  chlorosis  trouble, 
though  from  its  appearance  it  did  not  impress  us  as  being 
of  an  infectious  nature.  The  leaves  were  quite  prominently 
streaked  with  irregular  areas  of  lighter  yellowish-green,  the 
normal  green  color  remaining  more  commonly  around  the  veins. 
The  cause  of  the  trouble  was  not  determined,  though  possibly 
too  much  manure  in  the  beds  may  have  had  something  to  do 
with  it. 

SWEET  PEA,  Lathyrus  odoratus. 

Powdery  Mildew,  Erysiphe  Polygoni  DC.  Previous  to  this 
we  have  reported  in  this  state  only  one  trouble  of  the  sweet  pea ; 
viz.,  a  rot  disease.  This  powdery  mildew  forms  a  mealy,  whitish 
growth  on  the  leaves  through  the  production  of  its  conidial 
stage,  but  the  perithecial  stage  was  not  found.     Apparently  the 


736    CONNECTICUT   EXPERIMENT   STATION   REPORT,    I909-I9IO. 

mildew  is  not  a  conspicuous  parasite  of  the  sweet  pea,  as  it 
is  not  listed  on  this  host  in  the  more  prominent  works  on  the 
mildews.  The  absence  of  the  mature  stage  renders  its  deter- 
mination somewhat  doubtful,  but  as  the  conidial  stage  agrees 
with  the  above  species,  and  as  this  has  been  reported  on  several 
other  species  of  Lathyrus,  it  is  more  likely  to  be  this  than  any 
other  species. 

WALNUT,  ENGLISH,  Juglans  regia. 

White  Mold,  Microstroma  Juglandis  (Ber.)  Sacc.  We  have 
reported  this  fungus  before  on  cultivated  specimens  of  our 
native  butternut.  It  was  sent  to  the  writer  in  July,  1909,  by 
Dr.  R.  T.  Morris  on  the  variety  Kaghazi  of  the  English  walnut, 
grown  on  his  farm  at  Stamford.  While  this  fungus  forms 
conspicuous  white  patches  on  the  under  sides  of  the  leaves,  it 
is  not  usually  a  very  serious  pest. 

WHEAT,  Triticum  vulgare. 

Stinking  Smut,  Tilletia  foetens  (B.  and  C.)  Trel.  Very 
little  wheat  is  grown  in  this  state  at  the  present  time,  so  that 
this  smut  has  not  been  collected  here  in  the  fields.  However,  it  is 
of  economic  importance  in  another  way.  At  least  four  times 
during  the  last  few  years  samples  of  commercial  wheat  feeds, 
usually  in  the  shape  of  middlings,  have  been  sent  to  the  station 
for  examination  because  animals  refused  to  eat  the  feed.  Two 
of  these  samples  have  come  from  feed  men  and  two  from  farm- 
ers. A  microscopical  examination  in  each  case  has  shown  the 
presence  of  the  spores  of  the  stinking  smut.  In  a  sample 
recently  received  from  Mr.  R.  A.  Jones  of  Bethlehem,  the  smut 
spores  were  unusually  abundant.  Mr.  Jones  said  that  the  mid- 
dlings had  been  fed  to  hogs,  that  it  made  them  sick,  and  that 
some  of  them  refused  to  eat  more.  After  changing  to  other 
food  the  hogs  got  over  their  trouble. 

Feeds  that  contain  these  spores  indicate  not  only  that  they 
are  made  from  middlings,  but  from  badly  smutted  or  injured 
wheat,  which  would  be  of  no  value  for  flour.  Whether  or 
not  the  smut  spores  are  themselves  the  injurious  principle  might 
be  questioned,  but  there  seems  to  be  no  question,  if  they  are 
not,  that  the  action  of  this  fungus,  or  its  opening  the  way  for 


NOTES  ON   PLANT  DISEASES   OF   CONNECTICUT.  737 

bacteria  to  act,  produces  in  the  plant  tissues  deleterious  products 
that  injure  or  render  dangerous  their  use  for  feeding  purposes. 

Tubeuf,  in  the  English  edition  of  his  Diseases  of  Plants,  page 
306,  says  concerning  Tilletia  Tritici  (a  very  closely  related  smut, 
also  found  in  grain  in  this  country)  :  "The  smut  also  possesses 
poisonous  properties  which  make  flour  contaminated  with  it 
dangerous  to  human  beings  and  the  straw  or  chaff  injurious 
to  cattle.  .  .  .  The  symptoms  in  the  few  cases  of  disease  observed 
do  not  agree  very  closely.  A  paralyzing  effect  on  the  centers 
of  deglutition  and  the  spinal  cord  seem  to  be  regularly  present. 
As  a  result  one  generally  finds  a  continuous  chewing  movement 
of  the  jaws  and  a  flow  of  saliva,  also  lameness,  staggering, 
and  falling.  Cattle,  sheep,  swine  and  horses  are  all  liable  to 
attack." 

McAlpine,  in  his  Smuts  of  Australia,  page  8i,  records  a  case 
in  which  six  hundred  and  fifty  Leghorns  dropped  in  a  few  days 
from  a  daily  average  of  one  hundred  eggs  to  sixteen  when  they 
were  fed  on  smutted  wheat,  and  when  this  was  stopped  and 
clean  wheat  substituted,  they  regained  in  three  weeks  an  average 
daily  yield  of  eighty  eggs.  He  also  records  an  experiment  with 
pigepns  in  which  one  pair  was  fed  smutted  wheat  for  twenty- 
two  weeks,  while  the  other  pair  was  fed  sound  wheat.  The 
doves  fed  good  wheat  laid  seven  eggs  during  this  period,  while 
the  others  laid  only  two.  Both  pairs  of  pigeons  at  the  start 
were  in  good  plumage,  and  the  pair  fed  on  good  wheat  retained 
the  good  plumage  and  was  fat  at  the  end  of  the  experiment, 
while  the  other  pair  was  in  poor  condition,  with  the  feathers 
all  standing  out. 

While  writing  on  this  subject  of  deleterious  animal  foods, 
we  might  mention  that  we  have  also  occasionally  had  whole 
oats  sent  in  that  horses  refused  to  eat.  We  have  never  found 
any  fungus  that  might  be  the  cause  of  a  musty  condition  of 
these  oats.  It  has  been  thought  that  in  these  cases  the 
oats  were  bleached  by  some  sulphur  process,  and  that  this  had 
left  them  unpalatable  to  the  horses.  We  have  also  recently 
heard  of  a  case  where  certain  farmers  last  year  purchased  oats 
for  feeding  purposes,  and  as  they  looked  plump  and  white  they 
were  also  used  for  seed.  None  of  the  fields  sowed  with  these 
oats  came  up,  and  as  they  were  to  serve  as  a  cover  crop  for 
grass  seed,  the  latter  also  failed.     It  seems  quite  probable  that 


738    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

these  oats  had  been  sulphured,  and  their  vitality  entirely 
destroyed.  Seed  at  all  suspicious  should  be  sent  to  the  station 
to  have  its  germination  tested. 

We  have  also  had  one  or  two  cases  called  to  our  attention 
recently  where  animals  have  been  made  sick  and  some  have 
died  from  eating  silage.  In  such  cases  the  silage  had  not  been 
properly  made  and  had  become  moldy,  and  the  fungous  growths 
no  doubt  had  produced  poisonous  products  in  the  decomposition 
of  the  silage.  Similar  troubles  have  been  noticed  elsewhere 
from  feeding  moldy  silage  (see  Pammel's  Manual  of  Poisonous 
Plants,  p.  24). 


SPRAYING  POTATOES  IN  DRY  SEASONS.  739 

II.     SPRAYING  POTATOES   IN  DRY  SEASONS. 
General  Considerations. 

Object.  In  our  Report  for  1904,  page  363,  we  gave  the  results 
of  spraying  potatoes  during  the  three  wet  years,  1902  to  1904, 
when  bhght  was  unusually  severe  in  this  state.  The  sprayed 
parts  of  these  fields  showed  increased  yields,  varying  from  18 
up  to  108  per  cent.,  according  to  the  season,  thoroughness  of 
the  spraying,  etc.  During  these  experiments  certain  points  came 
up  for  consideration  upon  which  we  had  no  data  to  base  con- 
clusions. For  example :  ( i )  Would  manure  tend  to  increase 
the  amount  of  rot  in  a  field  badly  blighted  over  the  amount 
of  rot  in  the  same  field  in  which  a  commercial  fertilizer  was 
used?  (2)  Would  the  use  of  the  same  land  for  two  or  three 
years  in  succession  tend  to  increase  the  amount  of  rot  in  the 
successive  crops,  other  things  being  the  same;  and  would  blight 
tend  to  appear  earlier  in  such  a  field?  (3)  Would  ridging  the 
rows  help  to  prevent  the  blight  spores  from  being  washed  down 
to  the  tubers,  and  so  decrease  the  per  cent,  of  rot  as  compared 
with  level  culture  under  the  same  conditions? 

In  order  to  answer  the  above  questions,  the  writer  started  a 
series  of  experiments  in  1906,  which  were  carried  on  for  the 
four  years  ending  in  1909.  Unfortunately  for  the  primary 
objects  of  the  experiments,  these  years  proved  to  be  ones  in 
which  blight  did  very  little  harm  in  this  state.  In  fact,  in  three 
of  these  years  we  were  unable  to  find  any  of  the  blight  fungus 
on  potatoes  in  this  experimental  field,  and  in  the  other  year 
it  was  so  scarce  as  to  cause  practically  no  harm.  However, 
while  the  main  objects  of  the  experiments  remained  unanswered, 
we  still  obtained  data  regarding  spraying  in  dry  seasons,  also 
some  data  regarding  scab,  which  we  present  in  this  paper. 

Conditions  of  Experimentation.  The  experiments  were  carried 
on  each  year  on  the  same  plot  of  ground;  viz.,  two-thirds  of 
an  acre  of  level,  uniform,  light  loam,  with  a  very  leachy  subsoil, 
at  the  station's  temporary  experimental  farm  leased  of  Mr.  Webb 
at  Centerville.  This  land  had  not  been  cultivated  or  fertilized 
for  some  years  before  our  experiments  began,  and  so  was  in 
very  poor  shape  for  growing  crops  of  any  kind.  Amount  of 
yield,  however,  except  in  a  comparative  way,  was  not  contem- 
plated in  these  experiments. 

* 


740    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

The  land  was  divided  into  plots  as  follows :  The  east  half 
each  year  was  fertilized  with  manure  at  the  rate  of  sixteen  to 
eighteen  tons  per  acre,  while  the  west  half  received  about  the 
equivalent  of  the  nitrogen  in  the  manure  in  the  shape  of  two  ap- 
pHcations  of  nitrate  of  soda  (rate  of  450  lbs.  per  acre) .  Each  half 
received  the  same  amount  of  muriate  of  potash  (rate  of  300  lbs. 
the  first  and  second  years,  and  450  lbs.  the  other  two  years,  per 
acre)  and  bone  meal  (rate  of  200  lbs.  per  acre  each  year). 
As  the  manure  had  also  some  phosphorus  and  potash  in  it,  this 
naturally  gave  that  half  of  the  field  a  somewhat  better  fertili- 
zation than  the  half  on  which  sodium  nitrate  was  used,  and  as 
a  matter  of  fact  it  showed  this  each  year  in  a  more  luxuriant 
growth  and  a  larger  yield. 

Running  crosswise  of  the  manured  and  sodium  nitrate  halves, 
the  field  was  divided  into  halves,  one  of  which  received  level 
culture  and  the  other  modified  ridge  culture.  This  ridged  half 
was  really  cultivated  the  same  as  the  level  until  the  first  to  the 
middle  of  July,  when,  during  the  last  two  cultivations,  the 
potatoes  were  ridged  by  the  shovel  cultivators  as  much  as 
possible,  and  in  some  seasons  hilled  further  with  a  hoe.  In 
order  to  bring  the  tubers  in  the  level  culture  near  the  ground 
and  those  in  the  ridged  culture  as  deep  as  possible,  the  former 
were  planted  only  three  or  four  inches  deep,  while  the  latter 
were  planted  five  to  seven  inches.  Ordinary  cultivation,  not 
averaging  once  a  week,  was  given  the  whole  field.  Some  hand 
work  with  the  hoe  was  also  given.  Each  year  the  halves  given 
level  and  ridged  culture  were  reversed,  so  that  any  inequality 
of  land  might  be  cancelled. 

The  central  halves  of  the  ridged  and  level  cultivated  rows 
were  sprayed  with  Bordeaux  mixture  (4-4-50  formula),  leaving 
similar  unsprayed  rows  on  either  side.  Usually  about  three 
sprayings  with  Bordeaux  were  given,  and  as  these  were  made 
by  hand,  they  were  very  thorough.  The  first  spraying  was 
generally  given  about  the  middle  of  July,  and  the  last  about 
the  first  of  September.  All  the  potatoes  were  sprayed  for  insects, 
either  with  Paris  green  or  with  arsenate  of  lead,  so  as  to  make 
conditions  the  same  so  far  as  insect  injury  was  concerned. 

These  treatments  divided  the  field  into  eight  equal  areas,  each 
receiving  some  diflFerent  point  of  treatment,  as  follows :  ( i ) 
sprayed,   manured,   ridged;     (2)    unsprayed,   manured,   ridged; 


SPRAYING   POTATOES    IN    DRY    SEASONS.  74^ 

(3)  sprayed,  sodium  nitrate,  ridged;  (4)  unsprayed,  sodium 
nitrate,  ridged;  (5)  sprayed,  manured,  level;  (6)  unsprayed, 
manured,  level;  (7)  sprayed,  sodium  nitrate,  level;  (8) 
unsprayed,  sodium  nitrate,  level. 

The  potatoes  were  dug  in  October,  after  all  the  vines  were 
dead,  and  comparative  yields  determined  by  taking  the  counts 
and  weights  from  fifty-foot  lengths  in  two  separate  rows  of  each 
plot  for  comparison,  but  the  figures  given  in  the  tables  are  for  the 
combined  one  hundred  feet.  To  avoid  any  unevenness  due  to  the 
difference  in  the  land,  the  sprayed  and  unsprayed  rows,  which 
otherwise  received  the  same  treatment,  were  always  taken  as  near 
together  as  possible. 

Results.  Sprayed  versus  Unsprayed.  In  the  four  years,  out 
of  the  forty-four  comparisons  of  fifty  feet  of  sprayed  vines  with 
the  corresponding  unsprayed  vines,  the  sprayed  lots  in  every  case 
except  three  gave  a  greater  yield.  In  these  three  exceptions  the 
average  of  the  two  tests  of  fifty  feet  of  sprayed  vines  in  each 
case  was  greater  than  the  corresponding  average  of  the  two  fifty 
feet  of  unsprayed  vines,  so  that  it  can  be  stated  that  during  the 
four  years'  tests  the  sprayed  lots  invariably  gave  a  higher  yield 
than  the  unsprayed.  Table  i  gives  the  averages  for  the  four 
years  of  these  sprayed  and  unsprayed  potatoes,  and  from  this  we 
find  that  the  average  increase  of  all  the  sprayed  vines  over  un- 
sprayed vines  was  about  32  per  cent.  The  increased  yield  of  the 
sprayed  over  the  unsprayed  by  years  was  as  follows :  In  1906, 
30  per  cent. ;  in  1907,  24  per  cent. ;  in  1908,  17  per  cent. ;  in  1909, 
53  per  cent.  Plate  XXXVII  b  shows  the  comparative  yields  in  1906 
on  the  sodium  nitrate  half  (i)  sprayed,  ridged;  (2)  unsprayed, 
ridged;  (3)  sprayed,  level;  (4)  unsprayed,  level.  As  shown  in 
our  previous  experiments,  the  increased  yield  of  the  potatoes  was 
not  only  due  to  increased  numbers  of  marketable  tubers,  but  also 
to  increased  weight  of  the  tubers,  especially  the  larger  ones. 

In  every  one  of  these  years,  the  spraying,  theoretically,  more 
than  paid  for  itself,  despite  the  fact  that  none  were  blight  years. 
Stewart,  in  the  1906  Report  of  the  Geneva,  N.  Y.,  Experiment 
Station,  shows  that  out  of  fourteen  cooperative  experiments  with 
farmers  in  different  parts  of  the  state  in  1905,  it  cost  from  $2.44 
to  $6.84  per  acre  to  make  the  sprayings,  or  an  average  cost  for 
all  of  $4.25  per  acre.  We  think  that  in  this  state,  to  be  on  the 
safe  side,  we  may  estimate  the  cost,  including  bother,  of  spraying 


742    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

at  $10.00  per  acre.  It  often  requires  more  time  to  cart  water  and 
make  up  the  mixture  than  it  does  to  apply  it.  If  the  spraying  is 
done  by  hand,  it  also  costs  more  than  when  done  with  spraying 
machines,  but  a  more  thorough  job  can  be  done  in  this  way  with 
three  sprayings  than  with  five  by  any  power  sprayer  we 
have  seen.  Taking  the  cost  of  spraying  then,  at  $10.00  per  acre, 
and  the  average  yield  of  an  unsprayed  field  in  this  state  at  the 
conservative  figure  of  130  bushels  per  acre,  we  find  that  the  low- 
est increase  in  yield  due  to  spraying,  namely,  17  per  cent.,  means 
22  bushels,  and  the  highest  increase,  53  per  cent.,  means  69 
bushels.  At  the  very  low  price  of  fifty  cents  per  bushel,  the 
lowest  increase  would  mean  $11.00,  or  one  dollar  net  profit,  and 
the  highest,  $34.50,  or  $24.50  profit.  We  have  made  these  esti- 
mates especially  conservative  by  taking  comparatively  low  yields 
and  a  high  cost  of  spraying  per  acre.  Years  when  blight  really 
did  harm  in  the  fields  would  of  course  make  the  gains  very  consid- 
erably greater,  if  the  spraying  were  well  done.  ' 

The  question  naturally  comes  up,  why  did  the  sprayed  potatoes 
give  this  increased  yield  over  the  unsprayed  if  there  was  no  par- 
ticular injury  caused  by  the  late  blight  fungus?  Some  little 
benefit  was  no  doubt  derived  from  the  prevention  of  the  early 
blight,  but  this  must  have  been  scarcely  appreciable  because  this 
fungus  was  not  at  all  conspicuous  these  years.  Again,  some  very 
small  benefit  may  have  been  due  to  lessening  insect  attack,  since 
potatoes  sprayed  with  both  Bordeaux  and  Paris  green  keep  off 
the  insects  somewhat  better  than  where  sprayed  only  with  Paris 
green.  This  is  especially  true  as  regards  the  potato  flea  beetle. 
But  here  again  the  gain  was  of  a  very  minor  kind.  Ordinarily 
botanists  have  explained  this  increase  as  due  to  some  stimulative 
effect  the  Bordeaux  mixture  has  on  the  chlorophyll  of  the  potato 
leaves  in  increasing  starch  production.  Personally,  the  writer 
believes  that  the  results  are  largely  due  to  conservation  of  mois- 
ture in  the  leaves  in  dry  seasons  by  clogging  up  the  stomata  and 
zvater  pores  with  the  sediment  of  the  spray.  The  reasons  for  this 
belief  are  (i)  that  the  potato  leaves,  through  their  numerous 
stomata  and  terminal  water  pores,  lose  water  very  easily,  and  are 
especially  susceptible  to  what  is  known  as  tip  burn  in  dry  seasons ; 
(2)  that  the  unsprayed  vines  uniformly  suffered  earlier  and  more 
severely  from  tip  burn  than  the  sprayed,  which  were  green  for 
about  two  weeks  after  the  unsprayed  were  dead;    (3)   that  in 


SPRAYING  POTATOES  IN  DRY  SEASONS.  743 

1 910,  which  was  a  season  Hke  the  preceding  years,  except  with  a 
little  injury  from  blight  at  the  very  end  of  the  season,  spraying 
with  "Sulphocide"  and  commercial  lime-sulphur,  sprays  with 
comparatively  little  sediment,  did  not  prolong  the  Hfe  of  the 
vines  or  give  increased  yield,  while  spraying  with  Bordeaux 
mixture  did. 

Results:  Ridged  versus  Level  Culture.  As  to  the  primary 
object  of  these  two  methods  of  culture,  we  have  very  little  data, 
since  there  was  practically  no  rot  in  the  potatoes  during  the  four 
years.  We  hope  to  continue  the  experiment  until  seasons  favor- 
able for  rot  shall  give  us  data  on  this  subject.  That  there  is  some 
basis  for  the  belief  that  ridging  will  be  of  help  in  lessening  the 
rot  was  shown  in  our  experiments  in  1910  in  another  field,  where 
the  ridged  rows,  both  sprayed  and  unsprayed,  gave  practically  no 
rot  against  a  small  per  cent,  in  the  level  rows.  This  was  espe- 
cially true  of  the  unsprayed  level  rows,  which  gave  about  nine 
per  cent,  of  tubers  rotted  against  only  one-half  per  cent,  in  the 
sprayed  level  rows,  though  the  blight  appeared  on  the  foliage  only 
in  a  small  way  toward  the  end  of  the  season. 

While  our  data  are  not  very  enlightening  on  this  point,  still  the 
experiments  do  show  results  along  a  related  line,  namely,  that  the 
ridging  did  not  materially  lessen  the  yield.  There  are  those  in 
this  state  who  advocate  level  culture  because  of  the  supposed 
increased  yield  over  ridging,  and  if  this  is  so,  then  any  increased 
yield  due  to  prevention  of  rot  in  the  ridged  potatoes  might  be 
more  than  outbalanced  by  the  increased  yield  due  to  level  culture, 
especially  taking  the  yields  year  after  year,  many  of  which  show 
no  rot.  However,  with  our  modified  ridged  culture  (as  explained 
previously)  we  do  not  find  in  averaging  the  four  years  that  the 
ridged  potatoes  gave  any  very  materially  smaller  crop  than  the 
level,  since  the  average  of  the  latter  was  only  about  6  per  cent, 
higher  than  the  former,  and  to  offset  this,  the  19 10  crop  in  a 
different  field  slightly  favored  the  ridged.  Taking  the  yields  by 
years,  the  level  culture  gave  slightly  better  crops  in  1906,  1907, 
and  1908,  and  the  ridged  in  1909  and  1910.  As  these  last  four 
years  were  chiefly  drought  years,  the  test  was  even  more  severe 
than  it  v/ould  be  in  wet  seasons.  Likewise,  the  data  that  we 
obtained  in  some  cooperative  experiments  with  farmers  in  1906 
did  not  seem  to  show  that  the  ridged  potatoes  were  at  a  disad- 
vantage, judging  from  the  yields  given  and  the  general  opinion 
of  the  growers  where  no  measurements  were  taken. 
52 


744    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

In  connection  with  the  spraying,  it  may  be  noted  that  the 
averdge  for  the  four  years  gave  a  slightly  greater  proportional 
increase  in  the  sprayed  ridged  over  the  unsprayed  ridged  than 
was  given  by  the  sprayed  level  over  the  unsprayed  level,  on  both 
the  manured  and  the  sodium  nitrate  plots,  though  in  two  of  these 
years  (1907  and  1909)  the  proportional  increase  was  greater  for 
the  level.  This  perhaps  may  be  explained  by  the  unsprayed 
ridged  potatoes  suffering  on  the  whole  slightly  more  from  the 
droughts. 

Results:  Manure  versus  Sodium  Nitrate.  Here  again  we  did 
not  get  any  data  relative  to  whether  or  not  manure  increased 
the  amount  of  rot  in  fields  in  blight  seasons.  From  our  corre- 
spondence with  farmers,  they  seemed  to  favor  the  opinion  that 

manured  fields  rot  worse  than  those  where  chemical  fertilizers 

« 

only  are  used.  While  we  did  not  get  data  on  the  blight,  we  did 
obtain  data  regarding  scab  and  the  use  of  manure,  which  we  will 
mention  later. 

Of  course  the  manured  half  of  the  field  each  year  gave  a  greater 
yield  than  the  sodium  nitrate  half,  since  it  was  better  fertilized. 
The  average  increase  for  the  four  years  of  the  manured  over  the 
sodium  nitrate  was  about  47  per  cent.  There  is  no  doubt  that 
manure  is  a  very  good  fertilizer  for  potatoes,  but  at  the  same  time 
there  is  greater  danger  of  injury  from  scab  and  apparently  from 
rot  with  its  use.  The  most  sensible  way  to  use  manure  seems  to 
be  either  in  a  heavy  application  on  corn  the  previous  year,  using 
only  a  commercial  fertilizer  the  same  year  with  the  potatoes,  or 
at  least  to  put  it  on  the  land  and  plow  it  in  the  preceding  fall  rather 
than  in  the  spring  just  before  planting  the  potatoes,  as  was  done 
in  our  experiments.  As  regards  spraying,  the  sodium  nitrate 
sprayed  rows  uniformly  gave  a  higher  per  cent,  of  increase  over 
the  checks,  either  ridged  or  level,  than  did  the  sprayed  manure 
roAvs  over  the  unsprayed  checks.  We  are  not  sure  of  the  reason 
for  this,  unless  it  was  because  the  manured  rows  suffered  earlier 
and  more  severely  from  the  drought.  Our  manured  plot  also  had 
more  weeds  than  the  sodium  nitrate  plot. 

Results:  Scab.  These  experiments  showed  very  strikingly  how 
the  continued  use  of  the  same  land  for  potatoes  greatly  increases 
the  amount  of  scab.  Even  if  it  were  of  no  benefit  in  the  prevention 
of  rot,  rotation  certainly  is  of  value  in  lessening  scab.  The  first 
year  the  potatoes  were  on  the  land  the  per  cent,  of  scab  v/as  so 


SPRAYING   POTATOES    IN    DRY   SEASONS. 


745 


small  that  it  was  not  determined.  It  certainly  was  below  5  per 
cent.,  and  probably  not  over  i  per  cent.  The  second  year,  1907, 
the  scabby  tubers  had  increased  to  22  per  cent.,  in  1908  to  47  per 
cent,  (the  same  potatoes  in  our  general  rotation  fields  this  year 
gave  only  about  i  per  cent,  scabby),  and  in  1909  to  63  per  cent. 
The  last  two  years  the  scab  was  so  bad  as  to  seriously  affect  the 
market  value  of  the  potatoes.  The  scab  on  the  manured  half 
was  more  serious  than  on  the  sodium  nitrate  half,  since  the 
average  scab  for  the  three  years  1907  to  1909  for  the  former  was 
48  per  cent.,  while  on  the  latter  it  was  only  33  per  cent.  As 
regards  level  and  ridged  rows,  there  was  more  scab  in  1907  and 

Table  I. — Spraying  Experiments — Average,  1906,  1907,  1908  and  1909. 


(i)  Spraj'ed,  Manured,  Ridged 

(2)  Unsprayed,  Manured,  Ridged  .. 

(3)  Sprayed,  Sod.  Nitrate,  Ridged  ._ 

(4)  Unsprayed,  Sod.  Nitrate,  Ridged 

(5)  Sprayed,  Manured,  Level  _ 

(6)  Unsprayed,  Manured,  Level 

(7)  Sprayed,  Sod.  Nitrate,  Level 

(8)  Unsprayed,  Sod.  Nitrate,  Level  . 

Average — Spra3'ed 

Average — Unsprayed 


Very  large 

Large  to 
meaium 

Medium  to 
small 

Total 
marketable 

Very 

No. 

Wt. 

2 

No. 

Wt. 

No. 

Wt. 

No. 

Wt 

No. 

2 

77 

25 

161 

25 

240 

52 

82 

0 

0 

61 

19 

141 

21 

202 

39 

74 

3 

2J/2 

64 

20 

102 

14 

170 

3b 

40 

0 

0 

50 

14 

90 

12 

140 

25 

45 

2 

i^ 

7B 

2.S 

1^3 

27 

264 

54 

119 

I 

I 

68 

18 

168 

22 

236 

43 

151 

0 

0 

66 

20 

131 

17 

iq7 

3« 

74 

0 

0 

4.'5 

13 

116 

15 

162 

28 

80 

I 

I 

71 

23 

144 

21 

217 

45 

77 

0 

0 

5& 

16 

68 

17 

185 

34 

87 

1909  in  the  ridged  rows  and  less  in  1908,  and  in  the  average  for 
the  three  years  the  ridged  ran  slightly  higher,  though  whether  this 
means  anything  or  not  we  do  not  know.  As  the  level  and  ridged 
halves  were  alternated  each  year,  this  shows  that  it  was  the  same 
side  of  the  land  that  each  time  gave  the  most  scab,  and  so  the 
nature  of  the  land  rather  than  the  manner  of  cultivation  may  have 
been  the  determining  factor.  It  is  certain,  however,  that  the 
level  rows  suffered  much  more  from  sun  scald. 


Details  of  Experiments  in  igo6. 

Treatment.     May'  2:    Planted  with  Carmen  No.  3.     June  21: 

Sprayed  all  with  Paris  green.  July  6:  Gave  second  spraying  with 

Paris  green.  July  16:  Gave  first  spraying  with  Bordeaux  mixture 

(4-4-50)  by  hand.    Used  Paris  green  in  Bordeaux,  and  gave  un- 


746    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

sprayed  half  the  third  treatment  with  Paris  green,  as  bugs  were 
unusually  bad.  Also  gave  first  ridging  to  ridged  half  about  this 
time.  July  24:  Gave  final  ridging.  July  2'/:  Made  second  treat- 
ment with  Bordeaux.  August  8:  No  blight,  but  a  little  early 
blight  and  considerable  tip  burn,  especially  on  unsprayed  vines. 
Augiist  11:  Gave  third  spraying  with  Bordeaux.  Found  a  very 
few  blight  leaves  on  unsprayed  vines.  August  26:  Difference 
between  sprayed  and  unsprayed  vines  quite  marked  in  favor  of 
former,  due  to  tip  burn  and  insect  injury.  September  6:  Un- 
sprayed vines  fully  two-thirds  dead  from  tip  burn,  while  on  the 
sprayed  not  one-half  the  leaves  were  dead.    Gave  two  rows  only 

Table  II. — Spraying  Experiments  in  1906. 


(i)  Sprayed  (3),  Manured,  Ridged... 

(2)  Unsprayed,  Manured,  Ridged 

(3)  Sprayed  (4),  Sod.  Nitrate,  Ridged 

(4)  Sprayed  (3),  Sod.  Nitrate,  Ridged 

(5)  Unsprayed,  Sod.  Nitrate,  Ridged 

(6)  Sprayed  (3),  Manured,  Level 

(7)  Unsprayed,  Manured,  Level 

(8)  Sprayed  (4),  Sod.  Nitrate,  Level. 

(9)  Sprayed  (3),  Sod.  Nitrate,  Level. 

(10)  Unsprayed,  Sod.  Nitrate,  Level 

Average — Sprayed  (3) 

Average — Unsprayed 


Very  large 

Larj 
med 

'e  to 
ium 

Medi 
sm 

um  to 
all 

Total 
marketable 

Very 

small 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

5 

33/ 

154 

43 

159 

l^Vz 

318 

65^ 

28 

% 

0 

0 

125 

32U 

140 

H% 

265 

4i>y2 

22 

% 

2 

i^ 

167 

45U 

106 

12^ 

273 

sg'A 

15 

1/5 

5 

SVz 

122 

32  3^ 

134 

143^ 

261 

51 

16 

Vs 

0 

0 

103 

25 

109 

loi/. 

212 

35 'A 

22 

% 

8 

5 

171 

51 

166 

19?^ 

345 

ISVz 

35 

y. 

.3 

2^3 

140 

27 'A 

201 

20  3^ 

344 

boU 

29 

K 

2 

I'A 

159 

41 

15a 

iby2 

31S 

59 

24 

u 

0 

0 

146 

42  J^ 

143 

ibVz 

289 

583^ 

21 

% 

0 

0 

102 

29^ 

164 

nU 

266 

47 

26 

H 

3 

3 

148 

42 

150 

17 

303 

bi 

25 

'A 

I 

r 

117 

28 

153 

16 

272 

47 

25 

yi 

Rot 
No. 


2 

14 

5 
I 
r 
o 

4 
2 
o 

5 
I 
6 


a  fourth  treatment,  as  vines  were  too  far  gone  and  blight  was 
doing  no  particular  harm. 

Results:  It  is  a  question  whether  the  fourth  treatment  did  much 
good,  though  in  the  ridged  rows  it  gave  a  better  yield  than  the 
ridged  row  sprayed  only  three  times.  There  was  more  rot  this 
year  than  any  other,  yet  not  enough  to  do  any  harm.  Besides 
the  evident  difference  in  the  life  of  the  vines,  the  yield  also  showed 
a  corresponding  difference  in  favor  of  the  sprayed  rows.  The 
sprayed  (3)  manured  ridged  lot  gave  a  40  per  cent,  increased 
yield  over  the  unsprayed  manured  ridged,  as  compared  with  24 
per  cent,  increase  for  the  sprayed  manured  level  over  their  un- 
sprayed rows ;  the  sprayed  sodium  nitrate  ridged  gave  43  per  cent, 
increase  over  the  unsprayed  sodium  nitrate  ridged,  while  the 
sprayed  sodium  nitrate  level  gave  25  per  cent,  increase  over  the 


SPRAYING  POTATOES  IN  DRY  SEASONS. 


747 


unsprayed  check  rows.  The  average  of  all  the  sprayed  rows 
over  the  unsprayed  was  about  30  per  cent.,  or  the  second  best 
results  of  the  four  years'  test.  The  details  of  yields  are  given  in 
Table  II. 

Details  of  Experiments  in  ipoy. 

Treatment.    On  May  i  planted  Green  Mountain  variety.   July 

j;   Gave  first  application  to  all  rows  of  insecticide,  as  bugs  were 

late  in  starting  this  year.     July  8:    Gave  first  ridging  to  ridged 

half.     July  16:    Gave  first  spraying  with  Bordeaux,  and  used 


Table  III. — Spraying  Experiments  in  1907. 


Treatment     ( 


(i)  Sprayed  (3),  Manured,  Ridged 

(2)  Spraj^ed(2),  Manured,  Ridged 

(3)  Unsprayed,  Manured,  Ridged 

(4)  Sprayed    (3),     Sod.     Nitrate, 

Ridged 

(s)  Sprayed     (2),    Sod.     Nitrate, 
Ridged .-. 

(6)  Unspra3'ed,      Sod.      Nitrate, 

Ridged 

(7)  Sprayed  (3),  Manured,  Level. 

(8)  Sprayed  (2),  Manured,  Level. 

(9)  Unsprayed,  Manured,  Level. 

(10)  Sprayed   (3),     Sod.    Nitrate, 

Level    

(11)  Sprayed   (2),    Sod.    Nitrate, 

Level 

(12)  Unsprayed,     Sod.     Nitrate, 

Level   . 

Average — Sprayed  (3) 

Average — Unsprayed 


Very  large 

Large  to 
medium 

Medium  to 
small 

Total 
marketable 

Very  small 

Rot 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

0 
0 
0 

0 
0 
0 

19 
20 
21 

7 

143 
140 
112 

21^ 

21% 
17 

162 
160 
133 

28K 
29 

23^ 

164 

130 

97 

6^ 
5% 
4X 

0 
0 
0 

0 

0 

24 

7 

93 

12^ 

117 

19;^ 

87 

2% 

0 

0 

0 

33 

10 

96 

I3K 

129 

23% 

68 

2% 

0 

0 
0 
0 
0 

0 
0 
0 
0 

19 

13 

22 

9 

3'A 

92 
162 

155 
127 

r2>^ 

25K 
25X 

III 

175 
177 
136 

18 

91 
162 
130 
262 

4X 
10 

0 
0 
0 
0 

0 

0 

28 

m 

117 

14 

145 

22^ 

122 

3% 

0 

0 

0 

10 

3U 

118 

18^ 

128 

22X 

148 

S% 

0 

0 
0 

0 

0 
0 
0 

7 
21 

14 

2X 

7 
5 

102 

128 
108 

I5K 

19 

16 

109 
149 

122 

1714: 

26 

21 

149 

128 
150 

6X 

5 
6 

0 

0 
0 

Scab 
Per 
Cent. 


34 
41 
32 

10 

16 

35 
19 
16 
18 

14 


16 
20 
25 


insecticide  with  it  and  alone  on  unsprayed  vines.  July  ip:  Gave 
final  ridging  and  cultivation  of  potatoes.  August  3:  Made  second 
spraying  with  Bordeaux.  No  signs  of  blight,  but  tip  bum  bad, 
especially  on  unsprayed  potatoes,  and  showed  more  with  those  on 
manured  rows  than  on  sodium  nitrate  rows.  September  6:  Gave 
third  spraying  to  six  rows  only  (three  ridged  and  three  level), 
as  it  was  rather  late  to  do  much  good.  No  signs  of  blight  this 
season.  Unsprayed  vines  with  level  culture  more  uniformly  dead 
than  the  unsprayed  ridged.   Sprayed  rows  still  showing  consider- 


748    CONNECTICUT    EXPERIMENT    STATION    REPORT,    I909-I9IO. 

able  percentage  of  green  leaves,  especially  on  sodium  nitrate  part, 
but  difference  not  so  marked  as  in  previous  year. 

Results.  On  account  of  drought,  the  yield  this  year  was  con- 
siderably less  than  any  of  the  other  years.  The  third  spraying 
was  too  late  to  do  any  good  at  all.  If  the  first  spraying  had  been 
made  about  the  first  of  July  and  the  third  the  last  of  August,  the 
results  would  have  been  better.  The  sprayed  (3)  manured  ridged 
rows  gave  an  increase  of  20  per  cent,  over  the  unsprayed  manured 
ridged  portion,  while  this  was  increased  to  27  per  cent,  on  the 
sprayed  manured  level  over  the  corresponding  unsprayed  portion. 
The  sprayed  (3)  sodium  nitrate  ridged  rows  gave  only  8  per  cent, 
increase  (30  per  cent,  in  the  case  of  those  sprayed  twice)  over 
the  unsprayed,  while  the  sprayed  (3)  sodium  nitrate  level  gave  28 
per  cent,  over  the  unsprayed  portion.  The  average  increase  of 
all  the  sprayed  over  the  unsprayed  was  24  per  cent.  Table  III 
shows  details  of  yields. 

Details  of  Experiments  in  ipo8. 

Treatment.  On  April  2p,  planted  Green  Mountain  variety. 
July  5  to  10:  Gave  first  ridging.  Vines  were  sprayed  twice  with 
arsenate  of  lead  for  bugs,  which  were  not  bad  this  year.  July 
I/:  Gave  first  spraying  with  Bordeaux.  This  was  rather  late,  as 
the  tip  burn  was  already  evident,  especially  on  manured  half. 
July  2/:  Gave  second  spraying  with  Bordeaux.  Sodium  nitrate 
half  with  less  tip  burn  than  the  manured  half,  and  sprayed  vines 
somewhat  better  than  unsprayed.  August  ij:  Gave  third  spray- 
ing with  Bordeaux.  Very  little  early,  and  no  late  blight.  Sprayed 
rows  somewhat  better  than  unsprayed.  September  11:  Vines 
nearly  all  dead  except  a  few  scattered  ones.  Sprayed  vines 
showed  less  difference  over  unsprayed  this  year  than  any  other, 
due  no  doubt  to  the  fact  that  drought  was  bad  and  the  first  spray- 
ing was  not  given  until  tip  burn  began  to  show  its  effects^on  the 
vines.    No  blight  at  all. 

Results:  The  spraying  this  year  gave  the  least  results  of  any 
year,  showing  only  an  average  increase  of  17  per  cent,  over  the 
unsprayed.  Had  the  first  spraying  been  made  earHer,  there  would 
no  doubt  have  been  less  injury  from  tip  burn,  with  a  consequent 
increase  in  yield.  As  the  drought  affected  the  manured  rows 
most,  the  increased  yield  due  to  spraying  was  least  in  these.  The 
sprayed  manured   ridged  gave   12  per  cent,   increase  over   the 


SPRAYING  POTATOES  IN  DRY  SEASONS. 


7  49 


unsprayed,  while  the  sprayed  manured  level  gave  only  5  per  cent, 
increase  over  the  unsprayed  part.  On  the  other  hand,  the  sprayed 
sodium  nitrate  ridged  gave  46  per  cent,  increase  over  the  un- 
sprayed rows,  while  the  sprayed  sodium  nitrate  level  gave  20  per 
cent,  increase  over  the  unsprayed  portion.    See  Table  IV. 

Table  IV. — Spraying  Experiments  in  190S. 


(i)  Sprayed  (3),  Manured,  Ridged 

(2)  Unsprayed,  Manured,  Ridged 

(3)  Sprayed    (3),     Sod.     Nitrate, 

Ridged  

(4)  Unsprayed,      Sod.      Nitrate, 

Ridged  

(5)  Sprayed  (3),  Manured,    Level 

(6)  Unsprayed,  Manured,  Level. 

(7)  Sprayed     (3),     Sod.    Nitrate, 

Level    

(8)  Unsprayed,      Sod.      Nitrate, 

Level 

Average — Sprayed 

Average — Unsprayed   .- 


Very  large 


Large  to 
medium 


No.   Wt 


71 
56 

61 

44 
6g 

77 
40 

43 
60 

55 


20^ 


24  >^ 
24 

12% 

21 
17 


Medium  to 
small 


128 
126 

75 

67 
163 

158 


92 
122 
III 


20>^ 
20X 

CO 

23^ 

21^4 

I7X 

I2>^ 

18 

16 


■     Total 
marketable 


200 

182 

137 

III 

232 
235 

160 

135 
182 
166 


45X 
40K 

34 

23X 

48 

451^ 

243/ 

39 
33 


Very  small 


55 
103 


39 
108 

174 
76 

56 
68 
93 


2% 

3H 


3% 
5^ 

2^4 

2 

3 


Rot 
No. 


Scab 
Per 
Cent. 


46 
29 

23 

71 
58 

51 

43 
52 
43 


Details  of  Experiments  in  ipop. 

Treatment.  Used  Green  Mountain  variety  this  year,  not  plant- 
ing until  May  11,  as  the  season  was  late.  Gave  all  a  couple  of 
sprayings  with  arsenate  of  lead  for  bugs  on  June  24  and  July  7. 
About  the  middle  of  July  gave  first  ridging,  and  the  final  one  on 
July  27,  when  first  treatment  with  Bordeaux  was  also  made. 
August  p:  Made  second  spraying  with  Bordeaux.  September  2: 
Gave  third  spraying  with  Bordeaux.  Sprayed  rov/s  now  much 
greener  than  unsprayed,  especially  those  ridged,  as  the  vines  in 
the  unsprayed  ridged  rows  were  all  dead  from  tip  burn.  Sep- 
tember 28:  Vines  all  dead  except  one  here  and  there.  No  late 
blight,  and  very  little  early  blight.  Practically  all  of  premature 
dying  due  to  tip  burn. 

Results.  The  spraying  this  year  gave  the  best  results  of  any 
of  the  four,  since  the  average  increased  yield  was  53  per  cent. 
The  yields  this  year  were  better  than  any  other  year  except  1906. 
The  sprayed  manured  ridged  gave  an  increase  of  45  per  cent,  over 


75°    CONNECTICUT    EXPERIMENT    STATION    REPORT,    I9O9-I9IO. 

the  unsprayed  manured  ridged,  while  the  sprayed  manured  level 
gave  48  per  cent,  over  the  unsprayed  check.  On  the  other  hand, 
the  sprayed  sodium  nitrate  ridged  gave  60  per  cent.,  and  the 
sprayed  sodium  nitrate  level  79  per  cent,  over  their  unsprayed 
checks,  the  last  being  the  greatest  increased  yield  due  to  spraying 
obtained  in  any  of  the  experiments  during  the  four  years.  See 
Table  V. 


Table  V. — Spraying  Experiments  in   1909. 


(i)  Sprayed  (3),  Manured,  Ridged 

(2)  Unsprayed,  Manured,  Ridged 

(3)  Sprayed    (3),     Sod.     Nitrate, 

Ridged 

(4)  Unsprayed,      Sod.      Nitrate, 

Ridged 

(5)  Sprayed  (3),  Manured,  Level 

(6)  Unsprayed,    Manured,  Level 

(7)  Sprayed     (3),    Sod.    Nitrate 

Level    

(8)  Unsprayed,      Sod.      Nitrate 

Level    

Average — Sprayed 

Average— Unsprayed 


Very 

large 

Largre  to 

Medium  to 
small 

Total 
marketable 

Very 

small 

Rot 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

No. 

Wt. 

4 

VA 

64 

24'/^ 

212 

39>^ 

280 

67>^ 

79 

■h)i 

0 

0 

0 

44 

15 

185 

31/2 

229 

4(3/2 

73 

2% 

0 

5 

^% 

50 

18 

108 

17K 

163 

40 

28 

IX 

0 

0 

0 

^4 

11'/^ 

qi 

I3J4 

125 

25 

28 

IJ4: 

0 

0 

0 

61 

22 

242 

39  K3 

303 

61/2 

173 

5K2 

I 

0 

° 

46 

16 

184 

25K 

230 

41/2 

139 

i% 

0 

0 

0 

51 

i8>^ 

145 

21 

196 

39K 

78 

2X 

0 

0 

0 

2q 

q 

108 

13 

137 

22 

89 

^y^ 

0 

2 

2 

.S6 

21 

177 

2Q 

235 

52 

89 

3 

0 

0 

0 

38 

13 

142 

21 

180 

34 

82 

3 

0 

Scab 

Per 

Cent. 


77 


66 

67 
60 

65 


42 
62 
64 


Recommendations. 
(i)  Seed.  The  blight  fungus  carries  over  in  the  tubers,  and 
the  infected  ones  may  be  recognized  in  the  spring  by  the  slightly 
sunken,  often  pitted,  reddish-brown,  superficial  dry  rot.  While 
the  use  of  such  tubers  is  not  advisable,  still  blight  may  do  much 
harm  in  a  field  in  which  the  seed  tubers  were  perfectly  free  from 
the  fungus.  As  to  varieties,  we  know  of  no  good  standard  variety 
grown  in  this  state  that  is  not  subject  to  blight  of  the  vines  and 
rot  of  the  tubers,  though  there  may  be  more  variation  in  the  latter 
respect  than  in  the  former.  Such  varieties  as  have  been  found  by 
experiment  to  possess  more  or  less  resistance  to  either  blight  of  the 
foliage  or  rot  of  the  tubers  seem  to  have  it  at  the  expense  of 
quaHty  of  tubers.  However,  this  is  a  subject  for  further  investiga- 
tion, and  probably  offers  greater  possibilities  than  have  yet  been 
developed. 


SPRAYING   POTATOES    IN   DRY    SEASONS.  75  ^ 

(2)  Planting.  For  early  varieties  early  planting,  in  order  to 
mature  them  as  soon  as  possible  to  escape  injury  by  blight  or 
drought  in  midsummer,  is  no  doubt  advisable.  But  for  late 
varieties  we  rather  favor  only  medium  early  planting,  say  the  last 
of  April  to  the  first  week  of  May,  because  if  planted  too  early, 
late  potatoes  suffer  more  in  the  years  of  drought  than  if  planted 
later,  since  they  are  usually  so  far  matured  that  a  dry  July  or 
August  will  kill  them,  while  the  later  planted  fields,  especially  if 
sprayed,  will  manage  to  pull  through  until  the  moist  fall  season, 
and  so  really  have  a  longer  period  of  growth.  We  recommend 
that  the  seed  be  planted  fairly  deep,  five  to  seven  inches,  to 
develop  the  tubers  in  the  ground  as  deeply  as  possible  as  a  protec- 
tion against  rot  and  sun  scald. 

(3)  Rotation.  We  advise  rotation,  having  potatoes  on  a  dif- 
ferent piece  of  land  each  year.  A  four  years'  rotation,  such  as 
the  following,  is  not  bad  for  this  state:  (i)  Corn.  (2)  Potatoes. 
(3)  Rye.  (4)  Leguminous  crop  (sow  in  fall  with  the  rye,  or  the 
following  spring).  Growing  potatoes  on  the  same  land  two  or 
more  years  in  succession  increases  scab  and  possibly  in  favorable 
seasons  an  earlier  appearance  of  blight  and  greater  rot,  though  so 
far  as  the  blight  is  concerned  this  is  largely  conjecture. 

(4)  Fertilisation.  Manure  plowed  into  the  land  in  spring  just 
before  planting  the  potatoes  increases  the  amount  of  scab  and 
possibly  the  amount  of  rot  in  blight  seasons.  If  a  heavy  coat  of 
manure  was  used  with  the  com  the  previous  year,  commercial 
fertihzers  only  may  be  used  with  the  potatoes.  Or  if  manure  is 
used,  plow  it  in  the  preceding  fall.  Horse  manure  is  probably 
the  least  objectionable.  The  following  home-mixed  fertilizer  (per 
acre),  recommended  by  Dr.  Jenkins,  seems  to  merit  extended  use 
in  this  state:  Nitrate  of  soda,  150  lbs.;  muriate  of  potash,  200 
lbs. ;  acid  phosphate,  400  lbs. ;  tankage,  350  lbs. 

(5)  Cultivation.  We  recommend  a  thorough  cultivation,  to 
conserve  the  moisture,  in  the  nature  of  a  combined  level-ridge 
culture.  That  is,  give  the  vines  thorough  level  culture  up  to  the 
last  two  cultivations,  and  then  begin  sometime  early  in  July  to 
ridge  up  the  rows  with  the  shovel  cultivators,  moderately  at  first, 
and  as  much  as  possible  the  second  time.  After  both  of  these 
ridgings,  mulch  up  the  soil  between  the  ridges  by  shallow  cultiva- 
tion as  much  as  possible  without  pulling  down  the  ridges,  so  as  to 
hold  in  the  moisture.   This  ridging,  we  think,  protects  the  tubers 


752    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

more  against  rot,  by  burying  them  deeper  under  the  soil,  so  that 
the  blight  spores  are  not  washed  down  to  them  so  easily.  It  also 
gives  better  ventilation  to  the  vines,  by  allowing  water  on  the 
foliage  to  dry  off  quicker,  and  by  holding  the  vines  erect  and  off 
the  ground  makes  spraying  easier  and  more  effective. 

(6)  Spraying.  As  year  after  year,  wet  or  dry,  we  have  got 
increased  yields  due  to  spraying  potatoes  with  Bordeaux  mixture 
(4-4-50),  we  recommend  the  spraying  as  a  yearly  feature  in 
growing  late  potatoes  in  this  state.  The  spraying  should  be  done 
thoroughly,  whether  by  hand  or  by  power,  which  means  that  it 
will  take  from  two  to  three  barrels  of  the  mixture  per  acre.  With 
the  ordinary  horse-power  sprayers  using  fixed  nozzles,  it  is 
necessary  to  go  over  the  rows  twice,  in  opposite  directions,  at  each 
spraying,  in  order  to  properly  coat  the  vines.  The  first  spraying 
should  be  given  about  the  first  of  July,  and  if  desired,  an  insecti- 
cide, either  Paris  green,  rate  of  Yz  lb.,  or  arsenate  of  lead,  rate  of 
3  lbs.,  to  50  gallons  of  Bordeaux,  may  be  added.  AVe  do  not 
believe  from  our  trials  with  various  other  sprays  that  there  is 
anything  as  good  for  potatoes  as  the  home-made  liquid  Bordeaux 
mixture. 

For  the  late  blight  alone,  the  middle  of  July  is  early  enough  for 
the  first  spraying,  but  we  advise  the  first  of  July,  since  better 
results  against  tip  burn  and  early  blight  may  be  expected,  and 
then,  too,  by  the  middle  of  July  it  is  more  difficult  to  reach  the 
lower  parts  of  the  vines  when  a  luxuriant  growth  has  been  made. 
The  number  of  times  of  spraying  will  depend  upon  the  weather 
and  the  manner  of  spraying.  When  it  is  done  with  leads  of  hose 
by  men  on  the  ground,  only  three  or  four  sprayings  are  necessary. 
When  stationary  nozzles  attached  to  the  back  of  the  wagon  are 
used,  whether  the  power  is  furnished  by  hand  or  by  horse,  it  will 
take  from  four  to  seven  sprayings,  depending  on  the  weather,  to 
do  good  work.  In  any  case  it  is  essential  that  the  vines  be  kept 
covered  with  spray  up  to  the  time  of  their  death,  otherwise  the 
blight  may  develop  slowly  on  the  green  foliage  in  the  fall,  and 
while  doing  no  harm  in  preventing  tuber  formation,  may  work 
great  havoc  by  rotting  the  tubers  already  formed  by  the  spores 
washing  down  on  them.    See  Plate  XXXVII  a. 


OOSPORES  OF  POTATO  BLIGHT.  753 

III.     OOSPORES   OF   POTATO   BLIGHT,   Phytophthora 

infestans. 

Importance.  Very  few  fungi  have  caused  the  serious  and 
widespread  injury  that  in  certain  seasons  has  been  wrought  by 
the  potato  bhght.  So  great  was  this  damage  in  Europe  about 
1845,  that  three  governments  appointed  commissions  to  investi- 
gate the  trouble  and  determine  surely  the  cause,  as  there  was 
considerable  difference  of  opinion  on  this  latter  point.  In  North 
America  the  blight  was  very  destructive  at  the  same  time. 
Thoreau,  in  his  book  "The  Maine  Woods,"  written  about  1846, 
says :  "The  potato  rot  had  found  him  out  here,  too,  the  previous 
year,  and  got  half  or  two-thirds  of  his  crop,  though  the  seed  was 
of  his  own  raising."  A  similar  condition  existed  in  Canada,  as 
shown  by  a  letter  written  in  1844  to  Dr.  Bellingham  of  Dublin 
(see  Berkeley  in  Journ.  Hort.  Soc.  London  i :  11.  1846),  which 
reads  as  follows : 

During  the  months  of  July  and  August  we  had  repeated  and  heavy 
showers,  with  oppressive  heat  and  an  atmosphere  strongly  charged  with 
electricity.  Toward  the  close  of  the  month  of  August  I  observed  the 
leaves  to  be  marked  with  black  spots,  as  if  ink  had  been  sprinkled  over 
them.  They  began  to  wither,  emitting  a  peculiar  offensive  odor;  and 
before  a  fortnight  the  field,  which  had  been  singularly  luxuriant  and 
almost  rank,  became  arid  and  dried  up,  as  if  by  a  severe  frost.  I  had  the 
potatoes  dug  out  during  the  month  of  September,  when  about  two-thirds 
were  either  positively  rotten,  partially  decayed  and  swarming  with  worms, 
or  spotted  with  brownish  colored  patches,  resembling  flesh  that  had  been 
frost-bitten.  These  parts  were  soft  to  the  touch,  and  upon  the  decayed 
potatoes  I  observed  a  whitish  substance  like  mould. 

Concerning  the  condition  at  this  time  in  Europe,  Berkeley,  in 
the  article  mentioned  above,  writes  :  "Few  subjects  have  attracted 
more  attention,  or  have  been  more  variously  canvassed  than  the 
malady  with  which  potatoes  have  been  almost  universally  visited 
during  the  autumn  of  1845."  Since  that  great  outbreak,  which 
resulted  in  famine  in  Ireland,  the  blight  has  been  frequently 
reported  in  the  potato  districts  of  the  cooler  temperate  regions, 
but  only  under  special  conditions  of  moisture,  such  as  rainy  or 
foggy  weather  of  some  duration  in  July  and  August,  has  it 
developed  in  epidemics  of  widespread  and  unusual  importance. 


754    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I9O9-I9IO. 

When  the  writer  first  came  to  this  station  in  1902,  the  potato 
blight  was  at  the  height  of  one  of  its  periods  of  destructiveness. 
In  that  year  the  injury  resulted  largely  from  the  very  premature 
killing  of  the  vines,  some  fields  going  down  in  a  week  during 
the  latter  part  of  July.  In  1903  the  vines  were  killed  somewhat 
prematurely,  and  there  was  serious  rotting  of  the  tubers.  This 
tuber  rot  was  even  more  serious  in  1904,  being  in  fact  more 
destructive  in  this  respect  than  in  any  other  of  the  ten  years 
in  which  we  have  gathered  data.  Correspondence  at  the  time 
with  farmers  over  the  state  brought  out  the  following  items : 
J.  B.  Gelston,  East  Haddam, — "almost  a  total  failure" ;  Vine 
Hill  Farm,  Elmwood, — "lost  about  sixty  per  cent,  of  crop"  ;  W.  S, 
Thomas,  Groton, — "saved  about  one-third  of  crop" ;  W.  S.  Lee, 
Hanover, — "I  probably  lost  three-fourths  of  my  crop" ;  W.  M. 
Shepardson,  Middlebury, — "about  one-half  crop  rotted" ;  E. 
Healey,  Mystic, — "I  think  three-fourths  rotted  before  they  were 
dug" ;  C.  M.  Ladd,  North  Franklin, — "estimated  two-thirds  crop 
rotted."  Since  that  year  there  has  been  comparatively  little  injury 
in  the  state  from  blight,  especially  during  the  dry  years  from 
1907  to  1909.  In  1910  some  little  rot  started,  but  the  vines 
were  too  far  gone  from  tip  burn  before  the  appearance  of  the 
blight  for  it  to  get  a  good  start. 

With  the  reappearance  of  a  season  having  a  wet  or  muggy 
July  and  August,  we  may  expect  further  outbreaks  of  this  trouble. 
The  work  of  this  and  other  stations,  however,  has  shown  that 
much  of  the  injury  may  be  prevented  by  spraying  and  other 
protective  measures,  and  that  an  increased  yield  even  may  be 
expected  by  spraying  in  seasons  with  practically  no  blight.  (See 
preceding  article,  also  our  Report  for  1904,  p.  363.)  This  part 
of  our  object  in  studying  potato  blight  has  been  largely  accom- 
plished. 

Historical  Interest.  Another  feature  of  potato  blight  that  is 
of  especial  interest  is  its  historical  importance  from  a  botanical 
standpoint.  Some  idea  of  the  early  study  made  of  it  is  well 
illustrated  by  the  following  extract,  published  in  1846  in  The 
Amer.  Journ.  Sci.  and  Arts,  vol.  2,  page  281,  and  written  by  J.  P. 
Norton : 

Little  has  as  yet  been  done  on  any  organized  plan  in  this  country 
(United  States).  In  Europe  the  case  has  been  very  different.  In  Holland 
and  Belgium  a  committee  was  first  appointed  to  collect  facts  calculated  to 


OOSPORES   OF   POTATO    BLIGHT.  755 

throw  light  on  the  nature  of  the  disease.  In  one  of  the  Dutch  provinces, 
Groningen,  a  separate  commission  was  appointed  for  the  same  purpose. 
In  Germany,  Liebig,  among  others,  has  turned  his  attention  to  the  potato, 
and  has  lately  published  some  observations  on  its  nitrogenous  constituents. 
A  number  of  the  French  philosophers,  both  alone,  and  under  the  auspices 
of  the  Central  Society  of  Agriculture,  have  also  attended  to  the  subject. 
M.  Payen  has  lately  published  three  or  four  reports  containing  the  results 
of  elaborate  microscopic  and  chemical  researches.  The  English  govern- 
ment sent  a  commission  to  Ireland  of  three  distinguished  scientific  men, 
with  directions  to  obtain  as  much  information  as  possible  on  the  nature 
and  extent  of  the  disease.  In  Scotland  originated  the  most  extended 
schemes  of  all.  The  subject  was  taken  up  in  its  several  branches,  as  it  is 
connected  with  botany,  meteorology,  entomology,  and  chemistry.  Each 
branch  was  referred  to  a  competent  person,  and  the  investigation  is  still 
in  progress. 

Object  of  Investigation.  Many  investigators  since  have  made 
careful  studies  of  the  life  history  of  this  fungus.  Considerable 
interest  was  excited  by  the  Smith-De  Bary  controversy  concern- 
ing its  disputed  winter  spore  stage,  known  as  oospores.  It  is 
upon  this  point  that  the  writer  has  become  especially  interested 
by  reason  of  several  years'  study  of  the  fungus  in  artificial  cul- 
tures. Our  object  was  to  secure  these  oospores  in  cultures 
through  the  use  of  special  strains  of  the  fungus  or  by  particularly 
favorable  cultural  media,  since  in  our  first  cultures  no  indication 
of  their  existence  was  revealed.  In.  this  respect  we  have  finally 
been  successful,  though  their  abundant  production  has  not  yet 
been  accomplished.  We  have  made  a  special  study  of  cultural 
media,  environmental  conditions,  etc.,  in  the  hope  that  some  light 
might  also  be  thrown  on  the  related  question  why  certain  stages 
of  a  fungus,  usually  the«conidial  ones,  are  grown  readily  in  arti- 
ficial cultures,  while  other  stages,  usually  the  mature  one,  rarely 
if  ever  appear,  though  not  uncommon  in  nature.  We  cannot 
say  that  we  have  yet  accomplished  much  in  this  direction,  though, 
it  often  takes  tedious  preliminary  work  of  seemingly  little  impor- 
tance to  lead  up  to  the  final  successful  results. 

Previous  Work  by  Others.  We  have  referred  to  the  Smith- 
De  Bary  controversy,  carried  on  in  the  seventies  over  the  so- 
called  oospores  of  potato  bhght.  The  former  claimed  to  have 
found  these  sexual  spores  in  old  leaves  and  tubers  injured  by 
the  blight  fungus.  The  latter,  a  more  careful  investigator,  failed 
to  find  any  oospores  of  this  nature  that  he  could  connect  with 
the  blight  fungus,  and  he  threw  so  much  doubt  on  the  conclu- 


756    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

sions  of  Smith  that  botanists  generally  have  regarded  that  the 
existence  of  these  oospores  has  not  been  proven.  Since  that  time 
other  investigators  have  claimed,  on  a  few  occasions,  to  have  found 
bodies  like  immature  oospores.  The  writer  has  found  various 
suspicious  bodies  in  the  leaves  and  tubers  of  infected  plants, 
but  has  never  been  convinced  of  their  real  nature.  Some  of 
these  bodies  are  much  like  oospores  in  appearance,  but  in  our 
experience  they  have  never  been  so  abundant  or  typical  as  to 
convince  us  of  their  connection  with  the  blight  fungus.  Plate 
XXXIX  G-I  shows  some  of  these  bodies  which  are  easily  dis- 
tinguished from  the  true  potato  oospores  shown  above. 

Two  French  investigators,  Matruchot  and  Molliard,  were 
apparently  the  first  to  grow  the  blight  fungus  in  artificial  cultures. 
Their  reports  were  made  in  1900  and  1903.  They  were  not  suc- 
cessful in  gaining  any  Hght  concerning  the  oospores  from  their 
cultures. 

In  1904  the  writer  first  made  artificial  cultures  of  the  bhght 
fungus,  and  about  this  time  Jones  and  his  assistants  at  the  Uni- 
versity of  Vermont  took  up  the  study  of  the  fungus  in  the  same 
manner.  The  results  of  their  work  have  not  been  published 
in  detail,  though  the  main  points  have  been  presented  in  two 
papers  before  our  botanical  societies,  and  brief  abstracts  of  these 
have  appeared  in  Science.  In  their  work,  so  far  as  published, 
they  have  had  more  success  than  the  writer,  up  to  the  present 
investigation,  in  obtaining  curious,  immature,  and  apparently 
somewhat  abnormal  bodies,  apparently  of  an  oogonial  nature,  but 
whose  exact  identity  was  left  in  doubt,  since  there  were  no  signs 
of  antheridia  or  of  oospores.  The  writer  previously  has  been 
inclined  to  call  these  bodies  chlamydospores.  From  the  results 
of  our  present  investigations  we  believe  that  they  are  essentially 
abnormally  and  imperfectly  developed  oogonia  (possibly  function- 
ing as  chlamydospores)  due  to  lack  of  fertilization  by  normal 
antheridia. 

Previous  Work  by  the  Writer.  The  results  of  our  previous 
work  with  the  blight  fungus  in  artificial  cultures  have  been  pre- 
sented in  the  Reports  of  this  station  for  1905  (p.  304)  and  1908 
(p.  891).  In  these  investigations,  while  we  occasionally  obtained 
swollen  and  differentiated  threads  in  the  cultures,  we  were 
unable  to  produce  these  at  will,  or  to  further  their  development, 
so  their  nature  was  largely  a  matter  of  speculation.     Jones  and 


OOSPORES   OF   POTATO    BLIGHT.  757 

his  assistants  in  the  meantime  had  been  much  more  successful 
with  the  development  of  these  bodies,  but  with  culture  media 
much  less  suited  to  the  vigorous  development  of  the  fungus. 
Our  efforts,  however,  were  rewarded  at  the  time  by  learning 
how  to  best  obtain  cultures  of  the  fungus,  and  what  media  were 
best  suited  to  its  luxuriant  development.  In  this  respect  we 
believe  our  cultures  have  proven  better  than  any  of  those  yet 
attempted.  The  Lima  bean  juice  agar  described  in  our  Report 
for  1908  was  up  to  that  time  the  most  satisfactory  of  these  media. 
It  has  been  by  continued  efforts  to  develop  a  specially  favorable 
medium  that,  for  the  greater  part,  we  have  finally  accomplished 
the  desired  results. 

Present  Investigations. 

Nature  of  Work.  We  shall  give  in  the  following  pages  the 
general  results  of  our  recent  endeavors  to  produce  the  oospores 
of  Phytophthora  infestans  in  artificial  cultures.  A  short  prelim- 
inary account  of  this  work  has  recently  appeared  in  Science, 
vol.  XXXIII,  p.  744.  We  wish  here  to  acknowledge  indebtedness 
to  our  assistant,  Mr.  E.  M.  Stoddard,  who  has  made  most  of  these 
cultures  under  our  direction,  and  has  been  very  helpful  in  deter- 
mining the  results  thus  obtained,  since  it  has  required  hundreds 
of  cultures,  and  the  examination  of  these  several  times,  to  obtain 
the  required  data.  The  main  lines  of  procedure  have  been  to 
secure  favorable  strains  of  the  fungus  for  the  work,  and  to 
induce  these  strains  to  produce  oospores  by  means  of  favorable 
media  or  special  environment.  We  shall  discuss  these  points  in 
detail  in  the  following  paragraphs. 

Strains.  The  cultures  used  in  our  previous  work  were  lost  or 
allowed  to  die  out  from  time  to  time,  so  that  these  reported  here 
are  from  different  sources,  except  the  one  from  Holland.  These 
strains,  besides  representing  a  variation  in  origin,  also  present 
different  lengths  of  time  of  growth  in  artificial  cultures.  For 
example,  we  have  continuously  grown  the  Holland  strain,  A, 
for  over  two  years,  and  we  do  not  know  how  much  longer 
Professor  Jones  had  it  in  culture ;  while  the  E  strain  has  been 
cultivated  less  than  two  months.  There  seems  to  be  no  diminu- 
tion in  the  vigor  of  their  growth  under  continued  artificial  cul- 
tivation, though  we  do  not  know  whether  or  not  their  power  of 
infecting  potato  plants  has  declined.     They  all  still  retain  this 


758    CONNECTICUT    EXPERIMENT    STATION    REPORT,    I909-I9IO. 

power,  however,  as  determined  by  recent  tests.  These  strains 
are  designated  by  letters,  A,  B,  C,  etc.,  as  a  matter  of  easy  identi- 
fication. They  have  exhibited  some  sHght  variation  in  the 
luxuriance  of  their  mycelial  and  conidial  development,  and  even 
more  in  the  matter  of  oospore  production.  A  short  description 
of  their  source  of  origin,  development,  etc.,  follows : 

Strain  A.  This  was  obtained  about  February,  1909,  from  Jones,  who 
isolated  it  from  tubers  grown  in  Holland.  From  this  culture  we  have 
grown  at  least  twenty-two  generations,  represented  by  many  cultures  under 
varying  conditions.  It  has  formed  a  very  fair  growth  on  suitable  media, 
though  it  is  the  least  vigorous  now  of  any  of  the  strains.  It  was  the 
first  in  which  we  noticed  the  appearance  of  imperfect  o5gonial  formation, 
though  this  was  perhaps  more  owing  to  the  medium  employed  than  the 
strain,  since  the  B  strain  soon  afterwards  gave  even  better  results  in  the 
same  medium.  It  now  stands  about  fourth  in  the  matter  of  oospore  produc- 
tion, being  less  variable  than  D,  but  the  oospores  produced  are  never  very 
abundant,  and  are  usually  imperfect. 

Strain  B.  This  culture  was  isolated  by  the  writer  in  November,  1909, 
from  tubers  furnished  by  Mr.  Ellicott  Curtis,  and  grown  at  Bantam, 
Conn.,  that  year.  His  crop  had  been  sprayed  during  the  season  and  kept 
green  until  late  in  the  fall,  when  the  rains  washed  off  the  spray,  and  the 
blight  got  a  foothold  too  late  to  injure  the  vines  much,  but  enough  to 
thoroughly  infect  the  tubers,  which  were  dug  very  late,  and  found 
to  be  badly  rotted.  We  have  grown  this  strain  for  at  least  nineteen  genera- 
tions, perhaps  in  more  cultures  and  under  more  dififerent  conditions  than 
any  of  the  other  strains.  It  makes  a  good  vigorous  growth,  perhaps  the 
best  of  any,  though  not  always  the  most  luxuriant.  On  the  whole,  the 
best  results  in  oospore  production  have  been  obtained  with  it.  The  most 
perfect  oogonia,  antheridia  and  oospores  have  also  been  found  in  cultures 
of  this  strain. 

Strain  C.  Cultures  of  this  strain  were  obtained  by  the  writer  in  January, 
191 0,  from  infected  tubers  purchased  at  a  Westville  grocery,  and  probably 
grown  either  in  Maine  or  Long  Island.  About  fifteen  generations  have 
been  grown  in  cultures  after  the  manner  of  A  and  B.  For  a  long  time 
this  strain  gave  no  indication  of  oogonial  formation,  though  grown  con- 
tinuously on  the  medium  most  favorable  for  that  purpose.  About  the 
tenth  generation  immature  oogonia  were  first  noticed,  and  succeeding 
generations  developed  these  better  and  more  abundantly,  until  finally 
antheridia  also  began  to  appear,  and  somewhat  rarely,  mature  oospores. 
At  present  it  ranks  about  third  as  regards  oogonial  development.  It  ranks 
high  in  conidial  production. 

Strain  D.  This  strain  was  separated  by  the  writer  in  October,  IQIO, 
from  the  descendants  of  diseased  tubers  obtained  from  Mr.  Curtis  (see 
Strain  B)  and  grown  in  1910  on  our  experimental  farm  at  Centerville. 
It  has  the  general  characteristics  of  B,  and  has  given  some  cultures  with 
a  good  development  of  oogonia,  antheridia  and  mature  oospores,  but  as 


OOSPORES   OF   POTATO   BLIGHT.  759 

yet  it  seems  much  more  variable  than  B  in  this  respect,  and  so  not  to  be 
depended  on,  though  it  has  not  been  in  culture  nearly  so  long,  as  it  has 
been  carried  through  only  seven  generations.  However,  it  now  stands 
about  second  in  oospore  production. 

Strain  E.  Mr.  Stoddard  obtained  this  strain  in  February,  191 1,  from 
Maine  grown  tubers  purchased  at  a  local  grocery.  As  yet  it  has  not  been 
thoroughly  tested,  as  comparatively  few  cultures  have  been  made,  repre- 
sented by  only  three  generations,  but  in  these  oogonial  production  has  not 
made  its  appearance  even  in  a  slight  way. 

Media.  Synthetic  media,  because  of  known  composition,  offer 
the  best  means  for  determining  the  cause  of  oospore  production, 
if  such  depends  on  some  particular  chemical  substance  or  element. 
Yet  such  media,  especially  when  in  liquid  form,  are  not  as  favor- 
able for  general  growth  of  fungi  as  media  containing  vegetable 
nutrients  whose  ingredients  are  quite  complex  and  whose  exact 
chemical  nature  cannot  be  determined.  Consequently,  we  have 
not  used  synthetic  media  except  in  the  sense  that  certain  sub- 
stances of  known  composition  have  been  added  to  our  vegetable 
media  to  determine  their  individual  effect.  Potassium  and  phos- 
phorus are  more  or  less  fixed  in  literature  as  having  importance 
in  vegetable  reproduction,  and  yet  we  have  not  in  any  way  by 
the  addition  of  potassium  phosphate  increased  oospore  production 
in  our  cultures.  Likewise,  toxic  or  stimulative  substances  have 
an  influence  on  vegetative  growth,  yet  such  substances  as  we  have 
tried  in  a  small  way,  copper  sulphate,  chloroform,  ether,  etc., 
have  given  no  response  in  increased  oospore  production. 

Various  Media.  Most  of  our  cultures  have  been  on  vegetable 
media,  usually  in  combination  with  agar-agar.  We  have  tried 
some  few  liquid  media,  but  they  have  shown  no  special  advantage, 
such  as  might  be  expected  from  the  supposed  relationship  of 
Phytophthora  and  Pythium,  and  the  reported  favorable  develop- 
ment of  the  oospores  of  the  latter  in  liquids.  Likewise,  we  have 
not  found  gelatine  a  favorable  medium  in  what  little  use  we 
have  made  of  it,  though  this  was  used  largely  by  Jones  in  his 
cultures.  In  our  work,  besides  various  agar-agar  media^  we 
have  tried  a  considerable  variety  of  substances  and  combinations. 
We  have  used  living  aseptic  vegetable  tissues  and  quite  a  num- 
ber of  sterilized  ones,  either  in  whole  or  ground  condition.  We 
have  also  used  filter  paper  soaked  with  nutrient  liquid.  Taking 
into  consideration  all  of  the  various  media,  and  their  modifica- 

53 


760    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

tions,  we  have  tried  about  seventy-five  different  combinations 
in  over  1,200  cultures. 

Most  Favorable  Media.  Out  of  all  these  combinations,  three 
media  stand  out  as  being  especially  favorable  for  the  growth  of 
the  fungus.  Of  these  the  Lima  bean  juice  agar  was  described 
in  a  previous  paper.  (Report,  1908,  p.  898.)  This  has  never 
given  us  mature  oospores,  and  immature  ones  only  once.  A 
second  very  favorable  medium  for  aerial  growth  of  the  fungus, 
perhaps  the  most  favorable  of  any  we  have  used,  is  a  "combina- 
tion medium"  consisting  of  the  following  ingredients,  ground  to 
powder  in  a  food-chopper:  Lima  beans,  15  grms. ;  oats,  25 
grms. ;  peanuts,  10  grms,;  potato,  15  grms.;  sweet  com,  10 
grms. ;  wheat,  10  grms. ;  with  agar,  10  grms.,  and  water,  500  cc. 
This,  however,  has  shown  no  special  virtue  so  far  as  oospore 
production  is  concerned.  Potato  juice  agar  gives  a  fair  mycelial 
growth  of  the  fungus,  but  not  as  luxuriant  or  vigorous  as  the 
other  two  media  mentioned  here.  It  needs  to  be  used  for  the 
best  development  somewhat  stronger  than  we  first  tried  it,  and 
we  are  now  using  at  least  300  grms.  of  the  sliced  tubers  to  500  cc. 
of  medium.  But  potato  juice  agar,  like  the  preceding,  has  so 
far  been  of  no  value  in  producing  oospores.  The  one  medium 
that  has  stood  alone  so  far  as  production  of  oospores  is  con- 
cerned is  our  oat  juice  agar.  Without  this,  apparently,  we 
would  never  have  produced  perfect  oospores  in  cultures. 

Oat  Juice  Agar.  We  have  varied  somewhat  from  time  to 
time  in  the  manner  of  making  this,  but  in  order  to  have  as  uni- 
form a  product  as  possible,  we  have  finally  adopted  the  following 
method:  Fifty  grms.  of  ground  oats,  such  as  are  ordinarily  fed 
to  horses,  are  stirred  into  about  300  to  350  cc.  of  water,  and 
steam  from  an  autoclave,  by  means  of  glass  and  rubber  tubing 
connected  with  the  stopcock,  is  run  into  this  in  a  covered  dish 
for  half  an  hour.  This  cooks  the  material  without  burning  and 
at  a  uniform  temperature.  The  coarse  sediment  of  the  oats  is 
then  strained  off  through  an  ordinary  fine  wire  strainer,  and  10 
grms.  agar  is  added  to  the  liquid,  which  is  again  treated  to  the 
steam  for  half  an  hour  to  thoroughly  melt  the  agar.  Some  water 
passes  over  with  the  stream  during  these  cookings,  so  that  what 
little,  if  any,  is  needed  to  bring  it  up  to  the  required  500  cc.  is 
added  after  the  whole  is  drained  into  a  graduated  cyclinder. 
After  the  added  water  is  uniformly  distributed  by  repouring,  the 


OOSPORES   OF   POTATO    BLIGHT.  761 

medium  is  placed  in  the  test  tubes  and  these  are  sterilized  in  the 
autoclave  for  fifteen  minutes  under  7  to  10  lbs.  pressure. 

Chemistry  of  Oats.  We  are  not  sure  what  particular  ingredient 
of  oats,  if  any,  is  responsible  for  stimulating  oogonial  develop- 
ment in  the  oat  juice  agar.  Chemical  analyses  of  oats  show 
that  they  have  higher  percentages  of  ash,  fat,  and  lecithin  than 
the  other  cereals.  Taking  the  ash  content,  however,  it  seems 
that  this  higher  per  cent,  is  due  largely  to  silica,  so  that  the  per- 
centages of  phosphorus  and  potash  are  even  lower  than  in  most 
of  the  other  cereals,  as  well  as  in  beans,  though  perhaps  higher 
than  in  potatoes.  So  these  constituents  of  the  ash  are  apparently 
not  the  favorable  factors.  While  the  licithin  is  higher  than  in 
the  other  cereals  and  potatoes,  it  is  lower  than  in  beans.  On 
the  other  hand,  the  fat  is  considerably  higher  than  in  the  beans, 
or  any  other  cereal  except  conii,  which  it  slightly  exceeds. 

Lecithin  is  phosphorized  fat  (contains  fatty  acids,  cholin  and 
esters  of  phosphoric  acid),  and  is  more  soluble  than  ordinary  fat, 
being  the  form  in  which  it  is  said  by  some  to  be  digested. 
According,  to  Loew* :  "By  the  transformation  of  fatty  matter 
into  lecithin  the  higher  fatty  acids  are  offered  to  the  protoplasm 
in  a  soluble  form,  and  after  being  oxidized,  other  molecules  of 
fatty  acids  may  enter  into  the  place  of  the  former,  and  thus  the 
same  molecules  of  the  glycerol-phosphoric  acid  can  serve  repeat- 
edly as  vehicles  for  the  oxidation  of  fatty  acids."  In  this  man- 
ner the  amount  of  lecithin  really  available  in  the  oats,  because 
of  the  much  higher  per  cent,  of  fat,  may  greatly  exceed  that  of 
the  bean.  Lecithin  also,  according  to  Loew,  has  considerable 
therapeutic  value  in  cases  of  nervous  debility,  and  is  a  high  con- 
stituent of  the  nervous  system  (and  it  is  also  a  prominent 
constituent  of  the  spermatozoa  of  animals),  and  this  might 
explain  its  value  in  stimulating  the  potato  blight  to  sexual  repro- 
duction, especially  in  its  effect  on  the  antheridia,  which  seem  to 
have  most  nearly  disappeared. 

Fat  alone,  possibly  because  not  available  for  the  fungus,  does 
not  explain  the  production  of  these  oospores,  since  com,  though 
but  little  lower  than  oats  in  its  fatty  content,  did  not  stimulate 
their  production.  Likewise  peanuts,  very  high  in  fat  and  prob- 
ably higher  in  lecithin,  failed  to  even  produce  a  mycelial  growth 
of  this  fungus,  though  several  other  fungi  grew  rather  vigor- 


*Bull.  45  Bur.  PI.  Ind.  U.  S.  Dept.  Agr. 


762    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

ously  in  the  peanut  juice  agar.  The  fat  is  so  evident  in  this 
medium  that  it  shows  plainly,  even  when  only  25  grms.  of  ground 
peanuts  are  used  per  500  cc.  of  medium,  which  is  not  the  case 
with  our  oat  juice  agar.  While  the  comparatively  high  per  cent, 
of  fat  in  oats,  and  the  possibility  of  its  easy  conversion  into 
lecithin,  might  explain  the  phenomenon  of  oospore  production 
in  the  potato  blight  fungus,  we  have  no  sure  proof  that  this 
is  so.  In  any  case  the  fungus  seems  to  "feel  its  oats"  more 
or  less. 

Likewise,  this  oat  medium  seems  to  stimulate  ordinary  spore 
production  with  some  other  fungi.  For  example,  Monochcetia 
Desmazierii  fruits  abundantly  in  it,  whereas  it  does  not  fruit 
at  all,  or  very  little,  on  several  other  media  in  which  we  have 
grown  it.  We  have  also  several  times  had  the  sclerotia  of 
Sclerotinia  Libertiana  attempt  to  form  its  asco  stage  in  this 
medium,  by  developing  long  stalks  which  just  fail  to  expand 
and  develop  the  terminal  fruiting  cups.  Several  other  fungi  also 
produce  in  this  medium  a  more  luxurious  fruiting  condition  than 
they  do  in  the  other  media  in  which  we  have  grown  them. 

Environmental  Factors.  Having  secured  this  favorable  medium 
and  using  the  various  strains  at  hand,  we  have  attempted  to 
determine  if  certain  changes  in  the  medium  or  its  surroundings 
might  not  act  more  favorably  on  oospore  production.  We  will 
briefly  discuss  these  factors  in  the  following  paragraphs.  In 
summary,  however,  it  may  be  stated  that  we  have  not  found  any 
very  decidedly  favorable  factors,  though  there  seem  to  be  "ten- 
dencies" in  certain  directions,  and  that  as  yet  we  fail  to  uni- 
formly insure  or  gradually  increase  oospore  production  by  taking 
advantage  of  these  apparently  favorable  conditions. 

Acid  versus  Alkaline  Media.     As  made  up  by  us,  oat  juice 

N 
agar  takes  about  15  cc.  of  —  NaOH  to  neutralize  250  cc.  of  the 

natural  medium,  as  determined  by  the  phenolphthalein  test.     In 

order  to  test  the  effect  of  acid,  neutral,  and  alkaline  oat  agar 

the  following  strengths  were  made  at  different  times  and  the 

potato  blight  fungus  grown  in  them:    (i)    15  cc.  acid  (natural 

N 
medium)  ;    (2)  5  cc.  acid  (used  10  cc.  of  —  NaOH  to  neutralize 

N 
250  cc.  of  medium)  ;    (3)   neutral   (used  15  cc.  of  —  NaOH, 


OOSPORES  OF  POTATO  BLIGHT.  763 

etc.)  ;    (4)  5  cc.  alkaline  (used  20  cc.  of  —  NaOH,  etc.)  ;    (5) 

15  cc.  alkaline   (used  30  cc.  of  —  NaOH,  etc.)     The  strains 

A  to  D  acted  somewhat  differently  on  these  five  strengths,*  but 
as  a  rule  vigorous  mycelial  growth  occurred  only  on  the  15  cc. 
and  5  cc.  acid,  and  practically  no  growth  on  the  5  cc.  and  15  cc. 
alkaline  tubes.  However,  by  gradually  acclimating  the  various 
strains  through  the  different  strengths  from  the  natural  15  cc. 
acid,  they  were  all  finally  brought  so  that  they  would  grow 
more  or  less  on  the  15  cc.  alkaline  tubes. 

As  regards  oospores,  they  formed  less  abundantly  and  more 
im.perfectly  on  the  alkaline  tubes  than  they  did  on  the  acid  tubes. 
On  the  whole,  perhaps  the  5  cc.  acid  tubes  gave  the  best  results, 
though  in  some  of  the  comparative  tests  the  15  cc.  acid  and  the 
neutral  media  did  as  well  or  even  better.  We  had  thought  that 
perhaps  a  slightly  alkaline  medium  would  favor  oospore  produc- 
tion, since  in  previous  work  with  the  Lima  bean  mildew  (P.  Pha- 
seoli)  we  had  found  that  by  making  the  medium  slightly  more 
acid  we  had  first  cut  off  oospore  production,  then  conidial,  and 
finally  the  mycelial  development  itself,  and  our  first  results  with 
the  potato  blight  seemed  to  indicate  that  a  neutral  or  less  acid 
medium  than  the  natural  oat  juice  agar  favored  better  oospore 
development.  Out  of  the  total  of  our  experimentations,  how- 
ever, we  can  only  say  that  alkaline  oats  agar  is  apparently  less 
rather  than  more  favorable,  and  that  between  neutrality  and 
15  cc.  acidity  is  the  best  condition  for  oospore  production  as 
far  as  this  particular  factor  is  concerned. 

Light  and  Darkness.  Some  investigators  have  found  that 
light  favored  spore  germination  in  the  smuts.  We  tried  strong- 
light,  partial  and  total  darkness,  to  see  if  light  or  its  absence 
had  any  effect  on  oospore  production.  Cultures  kept  in  a  jar 
exposed  to  full  light  of  a  north  window  made  a  less  vigorous 
growth  than  those  kept  in  an  adjacent  jar  entirely  protected 
from  the  light,  while  neither  did  quite  as  well  as  the  cultures 
kept  under  our  usual  conditions  of  partially  diffused  light  (in 
the  same  room  in  a  glass  front  cupboard  in  open  tin  cans,  for 


*For  instance,  one  tube  of  C  grew  fairly  well  on  the   15  cc.   alkaline 
tube  when  transferred  directly  from  the  15  cc.  acid  tube. 


764    CONNECTICUT   EXPERIMENT   STATION    REPORT,    I9O9-I9IO. 

convenience  in  holding  them).  Neither  did  those  cultures 
exposed  to  the  stronger  light  or  those  in  total  darkness  show 
an  increase  in  oospore  production,  as  the  difference,  if  any,  was 
in  favor  of  our  ordinary  conditions  of  partially  diffused  light. 

Temperature.  The  fact  that  ordinarily  we  have  found  the 
oospores  of  P.  Phaseoli  on  beans  in  the  fall,  about  the  time  of 
the  first  frosts,  indicated,  as  is  the  case  with  many  other  fungi 
which  develop  their  mature  stage  in  late  fall  or  early  spring, 
that  cold  is  an  important  factor  in  the  production  of  the  sexual 
stage.  Our  experiments  along  this  line,  however,  gave  no  indi- 
cation that  oospore  production  in  the  potato  blight  could  be 
stimulated  in  this  manner.  Comparative  tests  were  made,  and 
repeated  with  similar  results,  under  four  different  conditions  of 
temperature,  the  temperatures  being  taken  three  times  a  day 
during  the  duration  of  the  tests,  (i)  Cultures  were  kept  in 
an  incubator  varying  from  29  to  33°  C,  and  averaging  32.6°. 
(2)  In  another  incubator  they  were  kept  at  a  temperature  of 
24  to  27°  and  averaging  24.6°.  (3)  Check  cultures  were  kept 
under  our  ordinary  room  conditions  of  16  to  22°,  averaging 
19.4°.  (4)  Cultures  were  kept  in  a  box  connected  with  an 
indirect  ventilator  to  the  outside  of  the  building,  in  which  the 
temperature  ranged  from  1.5  to  20°,  averaging  14.5°. 

The  results  of  these  tests  showed  that  the  fungus  failed  to 
grow  at  all  in  the  higher  temperatures  of  the  incubators.  The 
best  growth  was  made  under  our  ordinary  room  conditions,  where 
the  temperature  averaged  19.4°.  The  cultures  that  were  kept 
in  the  low  and  quite  variable  temperature,  averaging  only  14.5°, 
did  very  well  and  made  fair  growths  despite  these  conditions. 
It  would  seem  that  the  best  temperature  conditions  for  mycelial 
growth  of  the  fungus  were  between  1 5  and  20° . 

These  temperature  tests  agree  with  the  general  prevalence 
of  the  disease  in  our  more  northern  temperate  regions,  and  its 
most  severe  outbreaks  in  seasons  that  are  slightly  below  the 
average  in  temperature  as  well  as  above  it  in  moisture.  How- 
ever, in  spite  of  the  great  variability  with  those  cultures  grown 
under  the  colder  conditions,  there  was  no  indication  of  increased 
vigor  in  oospore  production.  In  fact,  these  tubes  did  no  better, 
if  as  well  as  the  check  tubes,  under  our  ordinary  temperature 
conditions.  Low  temperature,  then,  does  not  seem  to  be  the 
factor  determining  oospore  production  in  this  case. 


OOSPORES    OF   POTATO    BLIGHT.  7^5 

Air.  So  far  as  we  have  seen,  oospore  production  takes  place 
in  the  medium  sHghtly  below  or  at  the  surface  of  the  agar.  In 
fact,  this,  as  well  as  most  other  fungi  when  grown  on  agar 
media,  makes  only  a  slight  invasion  into  the  medium  itself. 
Jones,  in  his  experiments  with  this  fungus,  however,  seems  to 
have  used  stab  cultures  to  a  very  large  extent,  and  here  the 
oospore-like  bodies  were  produced  deep  in  the  medium,  away 
from  the  air.  We  have  not  used  stab  cultures  largely,  but  so  far 
as  we  have  tried  them  we  have  not  obtained  odspores  as  abun- 
dantly or  as  perfectly  developed  as  in  the  ordinary  agar  slant 
tubes.  Jones,  however,  used  gelatine  in  the  place  of  agar.  We 
have  not  used  this  in  our  work  nearly  so  much  as  the  agar,  but 
so  far  as  we  have  tried  it  we  have  not  found  it  as  desirable  as 
agar.  It  would  seem  from  our  work  that  the  exclusion  of  the 
air  by  stab  cultures  in  gelatine  media  was  not  necessarily  a  favor- 
able factor  in  oospore  production,  and  that  Jones  got  his  results 
in  spite  of,  rather  than  because  of,  this  condition.  Possibly  the 
strains  he  used  were  the  real  factors  in  his  partial  success. 

Moisture.  Moisture  seems  to  be  a  very  important  factor  in 
the  spread  of  the  potato  blight  fungus,  since  infected  leaves  of 
a  plant,  if  kept  in  a  dry  atmosphere,  develop  the  disease  no 
further.  Likewise,  in  cultures  there  seem  to  be  certain  condi- 
tions of  moisture  most  favorable  for  success,  but  here  excessive 
moisture  is  as  imfavorable  as  too  little  moisture.  Cultures  inocu- 
lated into  the  base  of  a  tube  containing  water  do  not  do  so  well 
as  those  inoculated  above  and  kept  free  from  the  water.  Like- 
wise, as  a  general  rule,  cultures  inoculated  toward  the  base  of 
a  tube  do  better  than  those  inoculated  in  the  drier  upper  edge. 
We  have  had  the  best  results  by  inoculating  the  tubes  at  the 
base,  if  not  bothered  by  water  there,  inserting  a  small  amount 
of  the  medium  with  the  fungus,  and  slightly  imbedding  this 
into  the  agar. 

The  chief  difference  in  a  tube  seems  to  come  in  the  production 
of  the  oospores,  which  if  present  are  most  likely  to  be  found 
in  the  upper  and  drier  part  of  the  tube.  Whether  the  passing 
of  the  fungus  from  the  more  moist  lower  portion  into  the  upper 
and  drier  portion  (dries  out  quicker  because  thinner)  explains 
this  we  do  not  know.  We  do  know  that  the  use  of  either  a 
more  or  less  dilute  agar  (we  ordinarily  use  lo  grm.  to  500  cc. 
of  water)   does  not  increase  oospore  production  to  any  appre- 


766    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

ciable  degree.  We  have  tried  rolled  tubes  in  a  few  cases,  inocu- 
lating them  at  the  base.  These  dry  out  much  quicker  than  the 
ordinary  slant  tube,  but  we  cannot  say  that  they  gave  us  any 
very  unusual  results.  We  have  also  tried  running  the  water, 
when  present  in  the  base  of  the  tubes,  over  the  growth  occasion- 
ally, and  have  pulled  off  the  aerial  growth  every  few  days,  but 
neither  of  these  methods  gave  us  unusual  results  as  regards 
the  oospores.  We  have  also  tried  growing  the  fungus  in  Petrie 
dishes,  which  offer  a  difference  in  moisture  conditions,  but  our 
luck  here  has  been  no  better  than  with  the  tubes. 

While  speaking  of  the  Petrie  dish  cultures  we  might  mention 
that  we  devised  methods  by  which,  with  temporary  slips  of  paraf- 
fined paper,  we  could  pour  a  plate  containing  from  two  to  four 
different  kinds  of  media.  Inoculating  these  at  the  center,  the  fun- 
gus gradually  spreads  out  over  theSe  different  media;  or  by  a 
special  contrivance  it  can  be  made  to  pass  successively  from  one 
kind  to  another.  But  these  variations  have  not  given  any  par- 
ticularly favorable  results  in  oospore  production. 

Clear  versus  Sedimentary  Media.  Besides  stab  cultures  in  a 
gelatine  medium,  a  third  factor  in  which  Jones'  methods  have 
differed  from  ours  has  been  his  use  of  a  clear  or  filtered  medium, 
while  we  have  largely  used  sedimentary  media,  in  which  only 
the  coarser  food  particles  have  been  filtered  off.  That  his  use 
of  filtered  media  does  not  explain  his  partial  success  in  imperfect 
oospore  production  seems  apparent,  since  we  failed  in  our  previous 
experiments  to  obtain  oospores  under  conditions  employed  by  him, 
so  far  as  the  use  of  stab  cultures  in  a  filtered,  potato  juice  gelatine 
goes.  So  it  must  be  some  other  factor  than  this  that  gave  him 
oogonia  where  we  failed  to  obtain  them.  In  fact,  we  have  found 
with  our  oat  juice  agar  that  the  sediment  in  the  medium  favors 
rather  than  retards  oospore  production. 

On  several  occasions  we  have  placed  a  batch  of  hot  oat  agar 
in  a  centrifuge  and  whirled  it  in  the  machine  for  ten  to  fifteen 
minutes,  until  it  hardened,  when  we  have  been  able  to  cut  off 
the  upper  perfectly  clear  portion  from  the  lower  portion  contain- 
ing the  extra  sediment.  Comparative  cultures  made  in  tubes 
of  the  clear  and  sedimentary  portions  have  always  shown  that 
the  fungus  makes  a  much  weaker  growth  in  the  former,  and 
so  far  no  signs  of  oospore  formation  have  been  found  in  it, 
while  in  the  sedimentary  tubes  the  mycelial  growth  and  oospore 


OdSPORES  OF  POTATO  BLIGHT.  767 

production  remain  about  the  same  as  in  our  ordinary  tubes,  from 
which  they  differ  only  in  a  Httle  more  sediment.  Tubes  made 
from  oats  in  which  none  of  the  coarse  sediment  is  removed 
also  act  about  the  same  as  our  ordinar}^  tubes  with  only  the  finer 
sediment  present.  Since  it  might  be  that  the  clear  tubes  were 
very  deficient  in  soluble  food  matter,  we  have  made  cultures  in 
which  the  ground  oats  were  soaked  over  night  in  water,  pro- 
tected from  bacterial  action  by  chloroform,  and  then  used, 
this  for  making  the  oat  juice  agar.  The  clear  and  sedimentary 
portions  of  such  a  medium,  separated  in  a  similar  manner  in 
the  centrifuge,  showed  no  different  results  than  before  on  inocu- 
lation with  the  fungus.  It  seems  from  these  experiments  quite 
evident  that  the  fungus  gets  from  the  solid  food  particles  in  the 
sediment  something  favorable  not  only  for  more  vigorous 
mycelial  development,  but  also  for  inciting  moderate  oospore 
production.  Whether  or  not  it  is  the  fat,  which  might  be  held  in 
greater  amount  in  the  sediment,  we  have  not  determined. 

Variability  of  Oospore  Production.  Despite  the  fact  that  oat 
juice  agar  will  usually  produce  oospores  with  most  of  our  strains, 
while  Lima  bean  juice  agar  practically  fails  to  do  so,  there  still 
remains  much  to  be  desired  in  stability  and  productiveness  of 
oospore  formation  in  this  favorable  medium.  In  fact,  we  are 
never  sure  even  now  when  Ave  make  a  culture  from  a  very  good 
tube  as  regards  oospores  that  its  descendant  tube  will  be  equally 
good.  While  our  success  in  obtaining  oospores  to-day  is  much 
greater  than  it  was  over  a  year  ago,  when  they  first  began  to 
appear,  it  is  only  in  looking  back  over  this  long  period  that  we 
notice  improvemerrt,  since  cultures  made  a  month  or  two  ago 
may  have  been  even  better  than  those  of  recent  date. 

Variability  in  the  Same  Tube.  Just  what  causes  this  varia- 
bility of  oospore  production  we  do  not  know,  since  it  manifests 
itself  even  in  the  same  tube.  We  have  mentioned  before  that 
ordinarily  we  are  more  likely  to  find  the  oospores  at  the  top  of 
the  culture  than  anywhere  else.  We  may  take  out  for  micro- 
scopic examination  small  pieces  of  the  medium  from  several 
different  places,  and  find  no  oospores,  or  only  a  few,  and  then 
we  may  strike  a  spot  where  they  are  rather  common.  This  may 
be  due  to  the  fact  that  localized  portions  of  the  mycelium  are 
concerned  in  their  production,  and  that  these  are  scattered.  We 
have  some  evidence  in  favor  of  this  view  in  the  oospore  pro- 


768    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

duction  of  P.  Phaseoli,  where  we  find  oospores  more  abundant 
in  some  places  than  in  others,  and  occasionally  we  find  them 
developed  in  more  or  less  luxuriant  bands,  so  evident  as  to  be 
detected  by  the  naked  eye.  Yet  with  this  species  it  is  rare  that 
they  do  not  occur  very  abundantly  in  every  slide  made  from  the 
surface  of  an  oat  agar  tube;  while  the  opposite  condition  is 
more  likely  to  be  true  of  the  potato  blight.  Perhaps  this  restric- 
tion and  scarcity  in  the  case  of  the  potato  blight  is  due  to  their 
development  in  certain  spots  where  the  available  food,  especially 
in  the  sediment,  is  most  abundant. 

Variability  in  Different  Tubes.  We  have  also  found  that  cul- 
tures made  from  the  same  source  into  tubes  of  the  same  batch  of 
the  medium  may  vary  considerably.  Perhaps  variation  in  dif- 
ferent batches  of  the  same  medium  might  be  accounted  for  by 
some  very  slight  variation  in  the  manner  of  making,  but  we 
would  hardly  expect  this  to  hold  true  in  the  same  batch  unless 
it  was  some  variation  in  the  settling  of  the  sediment,  too  slight 
to  be  detected  by  the  eye. 

We  have  tried  to  increase  oospore  production  by  propagating 
from  tubes  showing  the  greatest  luxuriance  in  their  development. 
While  there  seems  to  be  something  in  this,  still  on  the  whole 
we  have  no  very  clear  proof  of  it.  Perhaps  one  difficulty  in 
the  way  is  that  in  these  renewals  we  are  never  sure  that  we  have 
used  a  portion  of  the  culture  that  was  richest  in  oospore  produc- 
tion, since  it  is  usually  impossible  to  detect  their  presence  with 
a  hand  lens  in  our  uncleared  media.  With  Jones'  cleared  gelatine 
media,  however,  this  method  of  renewal  was  more  feasible, 
as  the  oospore  groups  were  quite  evident  with  a  hand 
lens,  and  this  may  account  for  such  success  as  he  has  attained  by 
his  continued  use  of  these  oogonial  groups. 

Age  of  Cultures  as  Regards  Oospore  Production.  As  a  usual 
thing,  with  our  oat  juice  agar  cultures  we  can  find  immature 
oospores  in  the  tubes,  if  such  appear  at  all,  two  weeks  after 
inoculation.  With  P.  Phaseoli  mature  oospores  are  usually 
quite  abundant  by  this  time.  In  order  to  be  sure,  however,  we 
have  usually  examined  the  tubes  again  about  a  month  after 
inoculation,  as  the  oospores  are  then  frequently  more  mature 
and  abundant.  One  of  the  very  best  tubes  produced  showed 
about  a  hundred  oospores,  in  different  stages  of  development, 
on  a  single  slide  from  it.     Ordinarily,  however,  the  number  of 


OOSPORES  OF  POTATO  BLIGHT.  7^9 

oospores  does  not  ran  over  from  six  to  twenty  on  a  slide,  and 
most  of  these  are  imperfect.  A  slide  that  will  give  two  or  three 
oogonia  from  which  mature  oospores  can  be  crushed  out  is 
considered  a  good  one.  Most  of  the  oogonia  fail  entirely  to 
mature,  apparently  through  lack  of  fertilization.  Those  that 
reach  maturity  with  a  perfect  oospore  usually  have  attached 
a  well-developed  antheridium.  Whether  or  not  we  can  develop 
oospore  production  to  the  luxuriance  which  is  the  usual  thing 
with  P.  Phase oli  in  both  Lima  bean  and  oat  juice  agar,  time  only 
will  tell.  What  we  are  sure  of  so  far  is  that  we  have  produced 
perfectly  matured  oogonia  with  normal  and  apparently  functional 
antheridia,  and  that  the  oogonia  in  such  cases  have  often  con- 
tained mature  and  apparently  functional  oospores.  As  yet  we 
have  not  germinated  these  oospores,  but  this  is  equally  true  of 
those  of  P.  Phaseoli,  as  it  apparently  takes  an  exposure  to  win- 
ter conditions  to  bring  about  germination. 

Microscopic  Characters  of  the  Oospores.  We  have  not  been 
able  to  follow  the  different  steps  in  the  development  of  these 
oospores  as  closely  as  in  the  bean  Phytophthora  because  of  their 
comparative  scarcity.  In  general  the  oogonium  develops  as  a 
much  more  prominent  factor  than  the  antheridium,  since  the  latter 
is  so  frequently  missing.  Then,  too,  the  oogonium  seems  to  be 
able  to  attain  a  much  more  advanced  stage  of  development  inde- 
pendent of  any  fertilization  than  does  P.  Phaseoli,  if  we  can  judge 
by  the  size  and  condition  of  the  oogonium  in  the  latter  when 
the  antheridium  first  appears.  The  oogonia  of  the  potato  fungus 
(see  Plate  XXXVIII)  first  made  their  appearance  in  our  cul- 
tures as  swollen  terminal  threads,  cut  off  from  the  normal  myce- 
lium by  a  septimi.  Not  infrequently,  by  bif ucation  of  the  mycelial 
thread,  there  were  two  of  these  swollen  bodies  together.  The 
terminal  portion  of  these  swollen  threads  gradually  assumes 
a  globular  shape  and  is  cut  off  from  the  rest  of  the  thread.  In 
the  meantime  the  swollen  thread,  especially  its  spherical  tip, 
becomes  more  or  less  deeply  tinted.  The  wall  is  thickened  by 
the  deposition  on  the  outside  of  the  original  coat  of  a  more  or 
less  irregular,  thick,  reddish-brown  coat  (see  Plate  XXXVIII  J). 
The  protoplasmic  contents  of  the  oogonium  may  now  begin  to 
contract  into  the  oosphere.  If  no  antheridium  is  present,  how- 
ever, this  seems  to  be  as  far  as  the  development  toward  an  oospore 
proceeds,  and  this  is  the  fate  of  most  of  the  oogonia. 


77°    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

When  an  antheridium  is  present  (see  Plate  XXXIX),  it  is 
very  similar  to  those  of  P.  Phaseoli.  We  have  not  yet  been 
able  to  detect  antheridia  in  their  younger  stages,  having  seen 
them  only  when  they  were  practically  mature,  and  the  oogonium 
is  then  well  along  in  its  development.  With  P.  Phaseoli  we 
found  that  the  antheridium  was  matured,  as  to  size  and  general 
appearance  at  least,  when  the  oogonium  was  just  beginning  to 
develop.  (See  Report,  1908,  Plate  LXXIV  E.)  Perhaps  a 
similar  condition  would  exist  with  the  potato  fungus  if  the 
antheridia  were  produced  as  abundantly.  The  presence  of  the 
antheridium  further  stimulates,  apparently  through  fertilization, 
the  protoplasmic  contents  into  forming  a  definite  spherical 
oospore  with  a  thin  limiting  cell  wall,  which  gradually  thickens 
until  there  is  formed  a  perfectly  normal  oospore.  Plate 
XXXIX  F  shows  an  oogonium  crushed  open  to  reveal  more 
plainly  its  enclosed  oospore,  well  filled  with  protoplasmic  con- 
tents. In  this  case  the  oogonium,  antheridium  and  oospore  are 
certainly  as  perfect  as  any  of  those  ever  produced  by  P.  Phaseoli 
(see  Plate  XL  A-C). 

The  thick,  colored,  outer  wall  of  the  oogonium  sometimes 
becomes  so  opaque  (see  Plate  XXXIX  D)  as  to  hide  all  signs 
of  its  oospore.  This  outer  coat  is  also  quite  variable  in  thickness 
and  in  the  irregularity  of  its  markings.  Apparently  the  medium 
in  which  it  is  grown  has  some  effect  on  the  irregularity  of  the 
markings  as  Jones  got  some  apparently  quite  abnormal  sculptur- 
ing on  those  grown  in  his  potato  gelatine  medium.  Then,  too, 
the  outer  wall  is  somewhat  brittle,  and,  when  slightly  crushed 
under  a  slide,  the  thick  walled  oogonia  appear  more  irregular 
than  they  really  are.  If  these  oogonia  were  produced  in  the 
plant  tissues  we  doubt  if  the  outer  wall  would  be  as  thick,  or 
present  as  great  irregularities  of  surface  as  it  does  in  the 
artificial  cultures.  Some  of  the  oogonia,  however,  are  very 
nearly  smooth,  and  some  have  rather  thin  walls  or  thin  places. 

The  oospores  have  a  medium  to  rather  thick  wall  when  mature. 
This  wall  is  smooth  and  hyaline,  though  in  some  cases  we  have 
seen  a  slight  tint  and  some  unevenness  of  surface.  Those  we 
have  measured  vary  from  24  to  35  fi  in  diameter.  The  oogonia 
vary  from  34  /x  to  50  fx,  mostly  38  to  42  ix,  depending  somewhat 
on  the  thickness  and  irregularity  of  their  outer  coat.  The 
antheridia  are  usually  somewhat  irregular-oval  in  shape,  vary 


OOSPORES   OF   POTATO    BLIGHT.  771 

in  size  usually  from  14  —  25  X  12  —  18 /x,  and,  like  P.  Phaseoli, 
often  show  the  superimposed  oogonial  thread  (see  Plate 
XXXIX  D-F).  We  have  not  been  able  to  trace  the  point  of 
origin  of  antheridium  and  oogonium,  but  they  seem  to  come 
from  separate  threads,  and  perhaps  it  is  the  contact  of  these 
threads  that  stimulates  the  beginning  of  their  development,  as 
seems  to  be  the  case  with  P.  Phaseoli. 

Hybrids.  In  our  Report  for  1908,  page  900,  we  described 
attempts  to  produce  hybrid  oospores  of  P.  injestans  and  P.  Pha- 
seoli by  inoculating  a  tube  of  Lima  bean  juice  agar  above  with 
the  former  and  below  with  the  latter  fungus.  At  first  we  v/ere 
inclined  to  believe  that  such  a  hybrid  resulted,  as  in,  around, 
and  below  the  P.  injestans  colony  there  were  developed  numerous 
oospores.  As  these  did  not  differ  essentially  from  those  of  P. 
Phaseoli,  however,  we  finally  came  to  the  conclusion  that  they 
all  belonged  to  the  latter  fungus. 

When,  however,  in  our  present  work  we  tried  this  same  cross- 
ing on  oat  juice  agar,  the  results  were  entirely  different,  since 
we  obtained  oogonia,  usually  only  in  the  vicinity  of  the  P. 
injestans  colony,  which  were  entirely  different  from  the  normal 
oogonia  of  P.  Phaseoli  that  were  produced  abundantly  all 
through  the  culture.  These  different  oogonia  were  oj  the  P. 
injestans  type,  which  at  that  time  we  were  just  beginning  to  get 
in  a  small  way  in  our  pure  cultures  of  P.  injestans  on  oat  juice 
agar,  and  they  differed  in  that  they  usually  produced  mature 
oospores,  and  were  jar  more  abundant  than  we  have  ever 
obtained  them  in  pure  cultures  oj  P.  injestans.  Plate  XL  shows, 
in  the  upper  row,  the  oogonia  of  P.  Phaseoli  as  grown  in  Lima 
bean  juice  agar;  the  second  row  shows  these  P.  Phaseoli 
oogonia  as  grown  in  a  cross  culture  in  oat  juice  agar  with  P. 
injestans;  while  the  two  lower  rows  show  the  hybrid  P.  injestans 
oogonia  as  appearing  in  the  same  culture  with  those  of  P.  Pha- 
seoli shown  in  the  row  above.  These  photomicrographs  easily 
convince  one  that  the  hybrid  oogonia  are  of  an  entirely  different 
type  from  those  of  P.  Phaseoli,  and  that  they  closely  resemble 
those  of  P.  injestans,  as  shown  in  Plate  XXXIX  A-F. 

As  stated  before,  they  differ  from  those  of  P.  injestans  in 
their  greater  abundance  and  more  perfect  development,  espe- 
cially of  the  oospores.  They  also  differ,  perhaps,  in  not  being 
so  deeply  tinted,  and  there  are  some  that  seem  to  grade  into 


772    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

P.  Phaseoli,  or  at  least  are  not  very  different  from  those  of  that 
species,  as  the  oogonial  walls  are  only  slightly  tinted  and  thick- 
ened. In  one  of  these  cross  cultures  we  measured  fifteen 
oogonia  and  oospores  each  of  P.  Phaseoli  and  the  hybrid  P. 
infestans,  and  found  that  in  the  former  the  oogonia  varied  from 
24  to  34  /i,  averaging  29  fi,  and  the  oospores  from  18  to  26  /a 
averaging  22.5  ja,  while  the  oogonia  of  the  latter  varied  from 
34  to  47  IX,  averaging  40  ix,  and  the  oospores  from  25  to  35  /*, 
averaging  30 /x.  These  hybrids,  then,  are  about  the  same  size 
as  the  uncrossed  oogonia  and  oospores  of  P.  infestans  when 
fully  matured. 

We  have  crossed  most  of  the  strains  of  P.  infestans  with  P. 
Phaseoli  on  two  diiferent  occasions.  Some  of  these  cross  cul- 
tures have  been  much  better  than  others  as  regards  production 
of  the  hybrid  oospores.  We  have  continued  these  hybrids  in 
renewal  cultures  in  some  cases  through  six  generations.  Plate 
XL,  L,  shows  one  of  these  oospores  in  the  fifth  renewal  from 
the  original  cross.  It  does  not  look  essentially  different  from 
the  original  hybrids,  as  its  lighter  color  is  not  lighter  than  some 
that  were  produced  in  the  original  crosses.  Now  in  these 
renewal  cultures  from  the  original  cross,  the  oospores  are  not 
descendants  of  the  hybrid  oospores,  since  these  never  germinate 
in  the  cultures,  but  apparently  are  merely  new  crosses  each  time, 
and  so  are  produced  only  by  the  conveyance  of  the  mycelia  of 
both  species,  which  became  closely  mixed  in  the  original  cul- 
ture. All  of  the  renewal  cultures  produce  an  abundance  of  the 
normal  oospores  of  P.  Phaseoli,  and  those  cultures  which  pro- 
duce few  or  none  of  the  hybrid  oospores  are  therefore  ones 
in  which  the  P.  infestans  mycelium  has  been  largely  or  entirely 
crowded  out  by  that  of  P.  Phaseoli. 

Of  course  there  are  those  who  may  think  that  these  oospores 
are  not  hybrids,  but  true  oospores  of  P.  infestans  which  have 
been  stimulated  to  oospore  production  in  some  way  by  the 
presence  of  P.  Phaseoli,  just  as  the  oat  juice  agar  has  stimu- 
lated this  production  to  a  less  degree.  We  do  not  believe  this 
to  be  the  case,  however.  The  potato  blight  has  evidently  lost 
its  power  of  antheridial  development  much  more  completely 
than  it  has  its  oogonial  development.  The  history  of  all  our 
cultures  shows  this  to  be  so.  In  these  cross  cultures,  the 
antheridia  of  P.  Phaseoli  take  the  place  of  the  missing  ones  of 


OOSPORES  OF  POTATO  BLIGHT.  773 

P.  infestans  when  situated  more  favorably  to  the  potato  oogonia 
or  oogonial  threads  than  they  are  to  their  own.  Naturally  they 
are  more  favorably  situated  on  the  whole  to  their  own  than  they 
are  to  those  of  the  potato,  and  so  the  hybrids  are  much  fewer 
in  number. 

Not  only  has  P.  infestans  been  crossed  with  P.  Phaseoli,  but 
also  with  P.  cactorum.  Our  results  in  crossing  with  the  latter, 
however,  have  not  been  nearly  so  satisfactory,  as  comparatively 
few  hybrids  were  found  in  the  cultures,  and  only  where  the 
B  and  the  D  strains  were  used.  We  think  that  this  is  probably 
due  as  much  to  mechanical  difficulties  in  having  the  antheridia 
of  P.  cactorum  free  to  fertilize  the  oogonia  of  P.  infestans,  as 
to  physiological  incompatibility.  Our  cultures  of  P.  cactorum 
on  oat  juice  agar  run  almost  entirely  to  oospore  production,  with 
little  or  no  aerial  growth  of  mycelium  and  conidiophores.  This 
makes  it  probable  that  the  antheridia  are  much  more  favorably 
situated  to  fertilize  their  own  oogonia  than  those  of  P.  infestans, 
so  that  the  chances  of  crossing  are  thereby  greatly  lessened. 
Those  hybrids  that  were  formed  were  of  the  potato  type,  but 
were  not  nearly  so  deeply  tinted  as  those  obtained  with  the  bean 
Phytophthora,  being  more  of  a  golden  than  a  chestnut  brown. 
Photomicrographs  of  the  normal  oospores  of  P.  cactorum 
in  a  cross  culture  with  P.  infestans  are  shown  in  Plate  XXXIX  J 
while  K  of  the  same  plate  shows  one  of  the  hybrid  oospores. 
Four  of  the  hybrids  had  oogonia  varying  from  35  to  40  /x,  and 
oospores  from  25  to  28  ijl,  while  the  variation  of  P.  cactorum 
in  the  same  culture  was  20  to  35  fi  for  the  oogonia  and  18  to 
28  fi  for  the  oospores.  The  oogonia  and  oospores  of  P.  cactorum 
are  very  similar  to  those  of  P,  Phaseoli,  being  hyaline,  smooth, 
and  moderately  thin- walled.  Sometimes  the  oogonia  of  both 
these  species  become  slightly  tinted. 

Theories.  At  one  time  we  suggested  as  a  reason  for  the 
absence  of  the  oospores  of  potato  blight  in  nature  and  cultures 
that  there  might  be  male  and  female  mycelial  strains  and  that 
oospore  production  could  therefore  take  place  only  when  these 
occurred  together.  So  far  as  our  culture  work  has  gone  with 
both  P.  Phaseoli  and  P.  infestans,  this  theory  does  not  seem 
to  hold  good,  as  we  explained  in  our  last  Report. 

The  more  probable  theory  is  that  the  potato  blight  fungus 
has,  at  least  in  most  instances,  lost  its  power  of  sexual  repro- 


774    CONNECTICUT   EXPERIMENT    STATION    REPORT,    I909-I9IO. 

duction  to  af  large  degree.  This  is  shown  by  failure  to  produce 
oospores  in  media  in  which  both  P.  Phaseoli  and  P.  cactorum 
produce  them  abundantly.  It  is  further  shown  by  oat  juice  agar 
stimulating  the  production  of  oogonia  in  varying  degrees  from 
imperfect  to  fully  matured  specimens,  and  by  the  varying 
response  of  different  strains  of  the  fungus  to  this  favorable 
medium. 

That  the  absense  of  oospore  production  is  due  more  largely 
to  the  absense  or  loss  of  vigor  of  the  male  than  the  female  fac- 
tor, is  shown  by  the  appearance  of  oogonia  in  cultures  more 
frequently  than  of  antheridia,  their  evident  attempt  to  form 
oospores  in  the  absence  of  the  latter,  and  their  success  when 
normal  antheridia  do  appear.  Likewise,  the  ease  with  which 
P.  infestans  crosses  with  P.  Phaseoli  seems  to  be  due  to  the 
vigorous  antheridia  of  the  latter  species. 

It  is  perhaps  idle  to  speculate  as  to  how  this  loss  of  sexual 
vigor  came  about,  though  it  may  be  due  to  the  same  cause  that 
has  induced  the  decline  of  sexual  reproduction  in  the  potato 
itself.  Very  rarely  do  the  blossoms  of  the  potato  set  seeds, 
apparently  due  largely  to  the  sterility  of  the  pollen.  Varieties 
long  propagated  seem  to  have  lost  the  power  of  seed  production 
more  completely  than  those  recently  originated,  especially  if  the 
latter  are  from  a  cross  with  a  species  nearer  the  wild  condition. 
This  loss  of  sexual  vigor  is  explained,  at  least  in  part,  by  the 
continued  propagation  of  our  cultivated  varieties  by  the  asexual 
tubers.  As  the  potato  blight,  so  far  as  is  known  in  nature,  carries 
over  from  one  season  to  another  only  through  the  vegetative 
mycelium  in  the  tubers,  it  may  be  that  continued  asexual  propaga- 
tion of  the  fungus  in  this  manner  has  also  resulted  in  its  loss 
of  sexual  vigor,  especially  of  the  antheridia. 


PLATE  XXXIII. 


<*    ♦ 


a.    Fruit  Spot  of  Apple,  p.  723. 


b.    Pocket  Curl  of  Azalea,  p.  724. 


FUNGI   OF  APPLE  AND  AZALEA. 


PLATE  XXXIV. 


a.    Showing  an  elm  defoliated  in  mid-summer. 


b.    Appearance  of  fungus  on  the  leaves. 
LEAF   SPOT  OF   ELM,  p    717. 


PLATE  XXXV. 


a.    Drought  injury,  followed  by  fungus,  p.  729. 


b.    Frost  injury,  p.  730.  Healthy 

INJURIES  OF  WHITE   PINE   SEEDLINGS. 


PLATE  XXXVI. 


a.    Pine-Currant  Rust,  p.  730. 


b.    Pine-Oak  Rust,  p.  728.      c.  Pine-Sweetfcrn  Rust,  p.  729. 
STEM    RUSTS  OF   PINES. 


I 


PLATE  XXXVII. 


i^  <^ ...  ^mV 

^                ifP^^HMk                «-^^^^^fe.-           .jl^ti^^jkw  """^ 

"M"^J,y  -^ -^v 

a.    Spraying  by  hand  with  stationary  nozzels. 


b.    Comparative  yields  from  sprayed  (1,3)  and  unsprayed  (2,  4)  vines,  p.  741. 
SPRAYING   EXPERIMENTS  WITH    POTATOES. 


PLATE  XXXVIII. 


■  'C***.       \ 


b 


B 


~F^ 


h— 


\y     ^S' 


>k  -  — c       C 


b 


L?", 


— e 


a.  mycelium;    b.  oogonial  thread  ;    c.  oogonium;    d.  ocisplierc;    e.  oospore; 

f.   antheridium. 


DEVELOPMENT  OF  OOGONIA  OF   PHYTOPHTHORA  INFESTANS,  p    769. 


PLATE  XXXIX. 


A-F.    Mature  oogonia,  oospores  and  antheridia  of  P.  infesfans,  p.  770. 
G-I.     Oogonia-like  bodies  found  in  bliglited  leaves  and  tubers  of  potatoes,  p.  756. 
J.     Oogonia  of  P.  cactoriivi  and  K,  hybrid  of  this  and  /'.  infcxiam,  p.  773. 


OOGONIA,  OOSPORES,  ANTHERIDIA  OF   PHYTOPHTHORA  sps,  etc. 


PLATE  XL. 


A-C,  P.  Phaseoli  grown  in  Lima  bean  agar.     D-F,  P.  Phaseoli  grown  in  same  tul)e 

of  oat  agar  with  P.  infestans.     G-L,  Hybrids  produced  by  fertilizing  /'. 

infesfaus  oogonia  with  antheridia  of  /*.  P/iasro/i,  p.  771. 


OOGONIA,  OOSPORES,  ANTHERIDIA  OF   PHYTOPHTHORA  sps. 


